VARIABLE CAPACITY PUMP AND WORKING OIL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINE

Info

Publication number: 20190219053
Type: Application
Filed: Aug 4, 2017
Publication Date: Jul 18, 2019
Applicant: HITACHI AUTOMOTIVE SYSTEMS, LTD. (Hitachinaka-shi, Ibaraki)
Inventors: Atsushi NAGANUMA (Atsugi-shi, Kanagawa), Hideaki OHNISHI (Atsugi-shi, Kanagawa), Yasushi WATANABE (Aiko-gun, Kanagawa), Koji SAGA (Ebina-shi, Kanagawa)
Application Number: 16/333,211

Abstract

Provided is a variable capacity pump where ease of control can be improved. A variable capacity pump includes a control chamber and a control valve. The control chamber is disposed between a pump accommodating chamber and a movable member, and the volume of the control chamber is variable with the movement of the movable member. Working oil discharged from a discharge portion is introduced into the control chamber. The control valve is provided in a passage and, with the movement of a valve element, the control valve varies the cross-sectional area of a flow passage, through which working oil in the control chamber is drained to a low pressure portion, while making the discharge portion and the control chamber communicate with each other.

Description

Description

TECHNICAL FIELD

The present invention relates to a variable capacity pump.

BACKGROUND ART

Conventionally, variable capacity pumps are known.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Laid-Open No. S59-70891

SUMMARY OF INVENTION Technical Problem

Conventional variable capacity pumps have room for improvement in terms of ease of control.

Solution to Problem

A variable capacity pump according to one embodiment of the present invention preferably includes a control portion which varies the cross-sectional area of the flow passage through which working oil in a control chamber is drained while making a discharge portion and a control chamber communicate with each other.

Accordingly, ease of control can be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram of a working oil supply system for an engine of a first embodiment.

FIG. 2 is a front view showing a portion of a pump of the first embodiment.

FIG. 3 is a schematic view of a control valve in the first embodiment.

FIG. 4 is a view showing an operation state of the pump of the first embodiment.

FIG. 5 is a view showing the operation state of the pump of the first embodiment.

FIG. 6 is a view showing the operation state of the pump of the first embodiment.

FIG. 7 is a graph showing the relationship between a duty ratio D of a solenoid in the first embodiment and the opening area S of a port.

FIG. 8 is a graph showing the relationship between a duty ratio D of the solenoid and a pressure p in a second control chamber, in the first embodiment.

FIG. 9 is a graph showing the relationship between a duty ratio D of the solenoid and an amount of eccentricity Δ of a cam ring, in the first embodiment.

FIG. 10 is a graph showing the relationship between a duty ratio D of the solenoid and a discharge pressure P, in the first embodiment.

FIG. 11 is a graph showing the relationship between an engine speed Ne and a discharge pressure P which are realized by the pump.

FIG. 12 is a graph showing a portion of FIG. 11 in an enlarged manner.

FIG. 13 is a schematic view of a control valve in a second embodiment.

FIG. 14 is a view showing an operation state of a pump of the second embodiment.

FIG. 15 is a view showing the operation state of the pump of the second embodiment.

FIG. 16 is a view showing the operation state of the pump of the second embodiment.

FIG. 17 is a cross-sectional view of a portion of a pump of a third embodiment.

FIG. 18 is a schematic view of a control valve in a third embodiment.

FIG. 19 is a view showing an operation state of a pump of the third embodiment.

FIG. 20 is a cross-sectional view of a portion of a pump of a fourth embodiment.

FIG. 21 is a schematic view of a control valve in the fourth embodiment.

FIG. 22 is a view showing an operation state of the pump of the fourth embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments for carrying out the present invention are described with reference to drawings.

First Embodiment

First, the configuration is described. A variable capacity pump (hereinafter referred to as “pump”) 2 of this embodiment is an oil pump used in a working oil supply system 1 of an internal combustion engine (engine) of an automobile. The pump 2 is disposed at a front end portion or the like of a cylinder block of the engine. The pump 2 supplies oil (working oil), which is a fluid having functions, such as lubrication, to respective slide portions of the engine, and to a variable valve device (valve timing control device and the like) which variably controls operation characteristics of a valve of the engine. As shown in FIG. 1, the working oil supply system 1 of the engine includes an oil pan 400, a passage 4, the pump 2, a pressure sensor (pressure measuring portion) 51, a rotational speed sensor (rotational speed measuring portion) 52, and an engine control unit (control portion) 6. The oil pan 400 is a low pressure portion which is disposed below the engine, and where working oil is stored. The passage 4 is disposed in the cylinder block, for example, and has an intake passage 40, a discharge passage 41, a main gallery 42, a control passage 43, and a relief passage 44. One end of the intake passage 40 is connected to the oil pan 400 by way of an oil filter 401. The other end of the intake passage 40 is connected to the pump 2. One end of the discharge passage 41 is connected to the pump 2. The other end of the discharge passage 41 is connected to the main gallery 42. An oil filter 410 and the pressure sensor 51 are provided in the discharge passage 41. The main gallery 42 is connected to the respective slide portions of the engine, the variable valve device and the like. The relief passage 44 is branched from the discharge passage 41, and is connected to the oil pan 400. A relief valve 440 is provided in the relief passage 44.

As shown in FIG. 2, the pump 2 is a vane pump. The pump 2 includes a housing, a shaft (drive shaft) 21, a rotor 22, a plurality of vanes 23, a cam ring 24, a spring (first biasing member) 25, a first sealing member 261, a second sealing member 262, a pin 27, and a control mechanism 3. The housing includes a housing body 20 and a cover. FIG. 2 shows the pump 2 from which the cover is removed. The housing body 20 has, on the inside thereof, a pump accommodating chamber 200, an intake opening (intake portion) 201, and a discharge opening (discharge portion) 203. The pump accommodating chamber 200 has a bottomed cylindrical shape, and opening of the pump accommodating chamber 200 is formed in one side surface of the housing body 20. A hole (shaft accommodating hole), in which the drive shaft 21 is accommodated, and a hole (pin hole), in which the pin 27 is fixed, are formed in a bottom surface of the pump accommodating chamber 200. The cover is mounted on the one side surface of the housing body 20 by a plurality of bolts, thus closing the opening of the pump accommodating chamber 200. One end of the intake opening 201 is open on the outer surface of the housing body 20, and the other end of the intake passage 40 is connected to the one end of the intake opening 201. The other end of the intake opening 201 is open on the bottom surface of the pump accommodating chamber 200 as an intake port 202. The intake port 202 is a groove (recessed portion) extending in a circumferential direction of the shaft accommodating hole, and is disposed on a side opposite to the pin hole with respect to the shaft accommodating hole. One end of the discharge opening 203 is formed in the bottom surface of the pump accommodating chamber 200 as a discharge port 204. The discharge port 204 is a groove (recessed portion) extending in a circumferential direction of the shaft accommodating hole, and is disposed on the pin hole side of the shaft accommodating hole. The other end of the discharge opening 203 is formed in the outer surface of the housing body 20, and one end of the discharge passage 41 is connected to the other end of the discharge opening 203. Grooves which correspond to the intake port 202 and the discharge port 204 of the housing body 20 are also formed on a surface of the cover which closes the pump accommodating chamber 200. The rotor 22, the plurality of vanes 23, the cam ring 24, and the spring 25 are disposed in the pump accommodating chamber 200.

The drive shaft 21 is rotatably supported on the housing. The drive shaft 21 is coupled to a crankshaft by way of a chain, a gear or the like. The rotor 22 is fixed to the drive shaft 21 in the circumferential direction. The rotor 22 has a columnar shape. A surface of the rotor 22 on one side in the axial direction has a recessed portion 221. A plurality of (seven) slits 222 extending in the radial direction are formed in the rotor 22. Back pressure chambers 223 are disposed on the inner side of the slits 222 in the radial direction. The outer peripheral surface 220 of the rotor 22 has projecting portions 224 which protrude outward in the radial direction. The slits 222 are open on the projecting portions 224. The vanes 23 are accommodated in the slits 222. An annular member 230 is provided in the recessed portion 221. The outer peripheral surface of the member 230 opposes the proximal ends of the respective vanes 23. An inner peripheral surface 240 of the cam ring 24 has a cylindrical shape. The outer periphery of the cam ring 24 has four protrusions 241 to 244 which protrude outward in the radial direction. The first sealing member 261 is mounted on the first protrusion 241. The second sealing member 262 is mounted on the second protrusion 242. The pin 27 is fitted in the third protrusion 243. As viewed in the axial direction of the cam ring 24, the first protrusion 241 and the second protrusion 242 are disposed on sides opposite to each other with respect to a straight line passing through the axis of the pin 27 and a center 24P of the inner peripheral surface 240 of the cam ring. One end of the spring 25 is mounted on the fourth protrusion 244.

On the inside of the pump accommodating chamber 200, a first control chamber 291, a first control chamber 292, and a spring accommodating chamber 293 are present between the housing and the cam ring 24. The first control chamber 291 is formed of a space defined between a portion of an outer peripheral surface 245 of the cam ring 24 ranging from the first protrusion 241 (first sealing member 261) to the third protrusion 243 (pin 27), and the inner peripheral surface of the housing (pump accommodating chamber 200). The first control chamber 291 is sealed by the first sealing member 261 and the pin 27. A first region 246 defined between the first sealing member 261 and the pin 27 on the outer peripheral surface 245 of the cam ring faces the first control chamber 291. A second control chamber 292 is formed of a space defined between a portion of the outer peripheral surface 245 of the cam ring ranging from the second protrusion 242 (second sealing member 262) to the third protrusion 243 (pin 27), and the inner peripheral surface of the housing (pump accommodating chamber 200). The second control chamber 292 is sealed by the second sealing member 262 and the pin 27. A second region 247 defined between the second sealing member 262 and the pin 27 on the outer peripheral surface 245 of the cam ring faces the second control chamber 292. The area of the second region 247 (angle subtended by the second region 247 in the circumferential direction of the cam ring 24) is slightly larger than the area of the first region 246 (angle subtended by the first region 246 in the circumferential direction of the cam ring 24). The width in the radial direction of a portion of the cam ring 24 which corresponds to the second region 247 (the end surface in the axial direction of the cam ring 24, the end surface being formed so as to continue to the second region 247, and opposing the bottom surface of the pump accommodating chamber 200) is larger than the width in the radial direction of a portion of the cam ring 24 which corresponds to the first region 246 (the end surface in the axial direction of the cam ring 24, the end surface being formed so as to continue to the first region 246, and opposing the bottom surface of the pump accommodating chamber 200) in average at least in a region which is disposed adjacent to the discharge port 204 in the radial direction. The spring accommodating chamber 293 is formed of a space defined between a portion of the outer peripheral surface 245 of the cam ring ranging from the first protrusion 241 (first sealing member 261) to the second protrusion 242 (second sealing member 262) via the fourth protrusion 244, and the inner peripheral surface of the housing (pump accommodating chamber 200).

The spring 25 is a compression coil spring. One end of the spring 25 is brought into contact with the surface of the fourth protrusion 244 on one side in the circumferential direction of the cam ring 24. The surface of the fourth protrusion 244 on the other side in the circumferential direction of the cam ring 24 opposes the inner peripheral surface of the pump accommodating chamber 200 (spring accommodating chamber 293), and is capable of coming into contact with this inner peripheral surface. The other end of the spring 25 is mounted on the inner peripheral surface of the pump accommodating chamber 200 (spring accommodating chamber 293). The spring 25 is in a compressed state. The spring 25 has a predetermined set load in an initial state, and always biases the fourth protrusion 244 to the other side in the circumferential direction.

The control mechanism 3 includes the control passage 43 and a control valve 7. As shown in FIG. 1, the control passage 43 includes a first feedback passage 431 and a second feedback passage 432. One end side of the first feedback passage 431 is branched from the discharge passage 41. The other end of the first feedback passage 431 is connected to the first control chamber 291. The second feedback passage 432 includes a supply passage 433, a communication passage 434, and a drainage passage 435. One end side of the supply passage 433 is branched from the first feedback passage 431. The other end of the supply passage 433 is connected to the control valve 7. One end of the communication passage 434 is connected to the control valve 7. The other end of the communication passage 434 is connected to the second control chamber 292. One end of the drainage passage 435 is connected to the control valve 7. The other end of the drainage passage 435 is connected to the oil pan 400.

As shown in FIG. 3, the control valve 7 is formed of an electromagnetic valve (solenoid valve), and includes a valve portion 8 and a solenoid portion 9. The valve portion 8 includes a cylinder (cylindrical member) 80, a spool 81, and a spring (second biasing member) 82. In FIG. 3, only the cylinder 80 is shown in cross section. The solenoid portion 9 includes a casing 90, a solenoid, a plunger, and a connector 92. The cylinder 80 is formed of a hollow member (cylindrical member), an inner peripheral surface 800 of which is cylindrical. One side of the cylinder 80 in the axial direction is open, and the cylinder 80 has a bottom portion 802 on the other side in the axial direction. A hole 809 penetrates the bottom portion 802 in the axial direction. The cylinder 80 has a plurality of ports. These ports are holes which penetrate the cylinder 80 in the radial direction, and each of these ports is open on the inner peripheral surface 800 and an outer peripheral surface 801 of the cylinder 80. These ports function as portions of the second feedback passage 432 together with the spaces on the inner peripheral side of the cylinder 80. The plurality of ports include a supply port 803, a communication port 804, and a drainage port 805. The supply port 803, the communication port 804, and the drainage port 805 are arranged in this order from one side to the other side in the axial direction of the cylinder 80. The other end of the supply passage 433 is connected to the supply port 803. The supply port 803 communicates with the discharge opening 203 through the supply passage 433 (second feedback passage 432) and the discharge passage 41. The supply port 803 allows working oil discharged through the discharge opening 203 to be introduced into the cylinder 80. One end of the communication passage 434 is connected to the communication port 804. The communication port 804 communicates with the second control chamber 292 through the communication passage 434. The communication port 804 allows the inside of the cylinder 80 and the second control chamber 292 to communicate with each other. One end of the drainage passage 435 is connected to the drainage port 805. The drainage port 805 communicates with the oil pan 400 through the drainage passage 435. The drainage port 805 can drain working oil from the inside of the cylinder 80.

The spool 81 is a valve element (valve) provided in the second feedback passage 432. The spool 81 is disposed in the cylinder 80 (accommodated in the cylinder 80), and is reciprocable in the axial direction of the cylinder 80 along the inner peripheral surface 800 of the cylinder. The spool 81 includes a first land portion 811, a second land portion 812, and a connecting portion 813. The first land portion 811 is disposed at the end of the spool 81 on one side in the axial direction. The second land portion 812 is disposed at the end of the spool 81 on the other side in the axial direction. The connecting portion 813 is disposed between the first land portion 811 and the second land portion 812, and connects both land portions 811, 812 with each other. The diameter of the first land portion 811 and the diameter of the second land portion 812 are equal to each other. The diameter of both land portions 811, 812 is slightly smaller than the diameter of the inner peripheral surface 800 of the cylinder. The connecting portion 813 is formed of a thin shaft portion. The diameter of the connecting portion 813 is smaller than the diameter of both land portions 811, 812. The respective land portions 811, 812 is in slide contact with the inner peripheral surface 800 of the cylinder.

A space 807 is defined between the first land portion 811 and the second land portion 812 as a liquid chamber in the inside of the cylinder 80. A space 808 is defined between the second land portion 812 and the bottom portion 802. The space 807 is defined by the inner peripheral surface 800 of the cylinder, the outer peripheral surface of the connecting portion 813, the surface of the first land portion 811 on the other side in the axial direction, and the surface of the second land portion 812 on one side in the axial direction. The space 807 has a cylindrical shape (annular shape). The supply port 803 is open to the space 807 in the initial state, and the communication port 804 is always open to the space 807. The drainage port 805 may be open to the space 807. On the inner peripheral side of the cylinder 80, the space 808 is defined between the surface of the second land portion 812 on the other side in the axial direction and the bottom portion 802. The drainage port 805 is slightly open to the space 808 in the initial state. The spring 82 is formed of a compression coil spring, and is disposed in the space 808. The space 808 functions as a spring chamber which accommodates the spring 82. One end side of the spring 82 is fitted on the outer peripheral side of a projection portion which projects from the second land portion 812 of the spool 81, and one end of the spring 82 is in contact with the end surface of the second land portion 812 on the other side. The other end of the spring 82 is in contact with the bottom portion 802. The spring 82 is in a compressed state. The spring 82 has a predetermined set load in the initial state, and always biases the spool 81 to one side in the axial direction. This spring force is defined as fs.

The solenoid portion 9 is joined to one side of the valve portion 8 in the axial direction, thus closing the opening of the cylinder 80 on one side in the axial direction. The solenoid portion 9 is an electromagnet which receives a supply of an electric current through the connector 92. The solenoid and the plunger are accommodated in the casing 90. The solenoid (coil) generates an electromagnetic force when energized. The plunger (armature) is made of a magnetic material, is disposed on the inner peripheral side of the solenoid, and is movable in the axial direction. The plunger is biased in the axial direction by an electromagnetic force generated by the solenoid. The first land portion 811 of the spool 81 is integrally joined to the plunger. The above-mentioned electromagnetic force biases the first land portion 811 (spool 81) to the other side in the axial direction. This electromagnetic force (thrust of the solenoid for propelling the spool 81) is assumed as “fm.” The solenoid can continuously change the magnitude of an electromagnetic force fm according to the value of an electric current supplied. The solenoid portion 9 is subjected to a PWM control, and the current value of the solenoid is given by a duty ratio D. An electromagnetic force fin varies according to duty ratio D (the current value of the solenoid). When a duty ratio D is less than a predetermined value D1 (dead zone), an electromagnetic force fm assumes zero, which is the minimum value (the electromagnetic force is not generated), regardless of the magnitude of the duty ratio D. When a duty ratio D is equal to or more than the predetermined value D1 and less than a predetermined value D2, an electromagnetic force fm varies according to the duty ratio D. With a larger duty ratio D, the electromagnetic force fm increases more. When a duty ratio D is equal to or more than the predetermined value D2, an electromagnetic force fin assumes the maximum value fmax regardless of the magnitude of the duty ratio D.

The pressure sensor 51 detects (measures) the pressure of working oil discharged through the discharge opening 203 of the pump 2 to the discharge passage 41. In other words, the pressure sensor 51 detects (measures) the pressure in the main gallery 42 (main gallery hydraulic pressure P). The rotational speed sensor 52 detects (measures) the rotational speed Ne of the engine (crankshaft).

The engine control unit (hereinafter, ECU) 6 controls the opening/closing of the control valve 7 (that is, the discharge amount of the pump 2) based on inputted information and an incorporated program. With such control, the pressure and flow rate of working oil to be supplied to the engine are controlled. The ECU 6 includes a reception portion, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and a drive circuit. The ECU 6 includes, as a main component, a microcomputer where these components are connected with each other through bidirectional common buses. The reception portion receives detected values of the pressure sensor 51 and the rotational speed sensor 52, and other information about engine operation conditions (oil temperature, water temperature, engine load and the like). The ROM is a memory portion which stores control programs, map data and the like. The CPU is an arithmetic operation portion which performs an arithmetic operation using the information inputted from the reception portion based on a control program which is read out. The CPU performs arithmetic operations for values, such as an electric current to be supplied to the control valve 7 (solenoid portion 9). The CPU outputs a control signal which corresponds to the result of the arithmetic operation to the drive circuit. The drive circuit controls an electric current to be supplied to the solenoid such that the drive circuit supplies electric power to the solenoid in response to the control signal outputted from the CPU. The drive circuit is a PWM control circuit, and causes the pulse width (duty ratio D) of a signal for driving the solenoid to be varied in response to the control signal.

During the operation of the engine, the control program is performed so that the control valve 7 (pump 2) is controlled. The ECU 6 causes a value (duty ratio D) of an electric current to be supplied to the solenoid to be varied such that the difference between a main gallery hydraulic pressure P and a predetermined required value P* falls within a predetermined range at any engine speed Ne within a predetermined range of rotational speed of the engine (Ne≥Ne1). Ne1 is a rotational speed which is set in advance. The required value P* is a hydraulic pressure, such as a hydraulic pressure required for operating the variable valve device, a hydraulic pressure required by an oil jet for cooling an engine piston, or a hydraulic pressure required for lubricating a bearing of the crankshaft. The required value P* is set in advance as an ideal value which corresponds to an engine operation condition, such as an engine speed Ne. The ROM of the ECU 6 stores, in the form of a map, required values P* for respective engine speeds Ne (according to the engine operation conditions). The map may set a discharge pressure, an oil temperature, a water temperature, an engine load and the like as parameters, for example. The ECU 6 causes a duty ratio D to be varied according to an engine speed Ne based on the map. The ECU 6 detects a main gallery hydraulic pressure P, and performs feedback control so as to cause the main gallery hydraulic pressure P to approximate a required value P*. The ECU 6 causes a duty ratio D to be varied such that the difference between the detected value and the required value P* for the main gallery hydraulic pressure P falls within a predetermined range. When an engine speed Ne is less than Ne1, the ECU 6 sets a duty ratio D to zero. When an engine speed Ne detected (measured) by a rotational speed sensor 52 is equal to or more than Ne1, the ECU 6 calculates the difference ΔP (=P*−P) between a hydraulic pressure P detected (measured) by a pressure sensor 51 and a required value P* at the above-mentioned (any) rotational speed Ne detected. When the magnitude of the difference ΔP is larger than a value ΔPset set in advance, a duty ratio D is caused to be varied such that the magnitude of the difference ΔP is reduced until the magnitude of the difference ΔP becomes equal to or less than the value ΔPset. When the magnitude of the difference ΔP is equal to or less than the value ΔPset, a duty ratio D is maintained (at a value immediately before a value at which the magnitude of the difference ΔP becomes equal to or less than the value ΔPset).

Next, the manner of operation is described. The cam ring 24 accommodates the rotor 22 and the plurality of vanes 23 so that a plurality of pump chambers (working chambers) 28 are defined. The rotor 22 and the plurality of vanes 23 function as elements (pump structures) which constitute the pump 2. Each working chamber 28 is formed (defined) by the outer peripheral surface 220 of the rotor 22, two vanes 23 disposed adjacent to each other, the inner peripheral surface 240 of the cam ring, the bottom surface of the pump accommodating chamber 200, and the side surface of the cover. The volume of each of the working chambers 28 is variable with the rotation. The volume of each working chamber 28 increases and decreases with the rotation and hence, the plurality of working chambers 28 function as a pump. Within a range which overlaps with the intake port 202 (intake region), the volume of the working chamber 28 increases according to the rotation, and the working chamber 28 takes in working oil through the intake port 202. Within a range which overlaps with the discharge port 204 (discharge region), the volume of the working chamber 28 decreases, and the working chamber 28 discharges working oil to the discharge port 204. The theoretical discharge amount (a discharge amount per one rotation), that is capacity, of the pump 2 is determined by the difference between the maximum volume and the minimum volume of the working chamber 28. The rotation of the crankshaft is transmitted to the drive shaft 21 of the pump 2 by way of the chain and the gear. The drive shaft 21 rotationally drives the rotor 22. The rotor 22 rotates in the counterclockwise direction in FIG. 2. When the pump structures including the rotor 22 are rotationally driven, working oil, which is introduced through the intake opening 201, is discharged through the discharge opening 203. A discharge pressure is introduced into the back pressure chambers 223, and pushes out the vanes 23 from the slits 222, thus improving liquid tightness of the working chambers 28. Also in the case where an engine speed is low so that a centrifugal force and a pressure in the back pressure chambers 223 are low, the annular member 230 pushes out the vanes 23 from the slits 222, thus improving the liquid tightness of the working chambers 28. The pump 2 sucks working oil from the oil pan 400 through the intake passage 40, and discharges the working oil to the discharge passage 41. The pump 2 pressure-feeds working oil to respective portions of the engine through the discharge passage 41 and the main gallery 42. When the pressure (discharge pressure) in the discharge passage 41 assumes a predetermined high pressure, the relief valve 440 opens so as to drain working oil through the relief passage 44 from the discharge passage 41.

The amount of variation in the volume of the working chamber 28 (the difference between the maximum volume and the minimum volume) is variable. The cam ring 24 is a member which is movable (movable member) in the pump accommodating chamber 200, and the cam ring 24 can perform a rotational oscillation about the pin 27. The pin 27 functions as a pivot portion (fulcrum) disposed in the pump accommodating chamber 200. The cam ring 24 performs a rotational oscillation so that the difference (amount of eccentricity Δ) between the axis (center of rotation) 22P of the rotor 22 and the axis (center) 24P of the inner peripheral surface 240 of the cam ring varies. Varying the amount of eccentricity Δ varies the amount of increase or decrease in volume (amount of variation in volume) of each of the plurality of working chambers 28 at the time of rotating the rotor 22 and the plurality of vanes 23. That is, the pump 2 is a variable capacity pump. Accordingly, increasing the amount of eccentricity Δ allows capacity to be increased, and reducing the amount of eccentricity Δ allows capacity to be decreased. Further, the volume of the first control chamber 291 and the volume of the second control chamber 292 can be varied with the movement of the cam ring 24.

The cam ring 24 is biased by the spring 25 to one side (to the side where the amount of increase or decrease in volume of each of the plurality of working chambers 28 increases, and the amount of eccentricity Δ increases) in the rotational direction about the pin 27. This spring force is defined as “Fs.” The cam ring 24 receives the pressure of working oil in the first control chamber 291. The first region 246 of the outer peripheral surface 245 of the cam ring functions as a pressure receiving surface which receives a pressure in the first control chamber 291. The cam ring 24 is biased to the other side (to the side where the amount of eccentricity Δ decreases) in the rotational direction about the pin 27 by the above-mentioned hydraulic pressure. A force generated by this hydraulic pressure (hydraulic pressure force) is defined as “Fp1.” The volume of the first control chamber 291 increases with the movement of the cam ring 24 to the other side (the direction opposing the biasing force Fs of the spring 25) in the above-mentioned rotational direction. The cam ring 24 receives the pressure (control hydraulic pressure) p of working oil in the second control chamber 292. The second region 247 of the outer peripheral surface 245 of the cam ring functions as a pressure receiving surface which receives a control hydraulic pressure p. The cam ring 24 is biased to one side in the above-mentioned rotational direction by the control hydraulic pressure p. A force generated by the control hydraulic pressure p (hydraulic pressure force) is defined as “Fp2.” The volume of the second control chamber 292 increases with the movement of the cam ring 24 to one side (the same direction as the biasing force Fs) in the above-mentioned rotational direction. The position of the cam ring 24 in the rotational direction (the amount of eccentricity Δ, that is, capacity) is mainly determined by hydraulic pressure force Fp1, hydraulic pressure force Fp2, and biasing force Fs. When a hydraulic pressure force Fp1 becomes larger than the sum of hydraulic pressure force Fp2 and biasing force Fs (Fp2+Fs), the cam ring 24 oscillates to the other side in the above-mentioned rotational direction so that the amount of eccentricity Δ (capacity) reduces. When a hydraulic pressure force Fp1 becomes smaller than the sum of hydraulic pressure force Fp2 and biasing force Fs (Fp2+Fs), the cam ring 24 oscillates to one side in the above-mentioned rotational direction so that the amount of eccentricity Δ (capacity) increases.

Working oil discharged through the discharge opening 203 (hydraulic pressure P of the main gallery 42) is introduced into the first control chamber 291 through the first feedback passage 431. Working oil discharged through the discharge opening 203 (main gallery hydraulic pressure P) may be introduced into the second control chamber 292 through the second feedback passage 432 (the supply passage 433, the control valve 7, and the communication passage 434). Working oil in the second control chamber 292 may be drained through the drainage passage 435. The control valve 7 can control an introduction of working oil into the second control chamber 292 and drainage of working oil from the second control chamber 292. The spool 81 moves so as to switch the connection state of the passage. To be more specific, the first land portion 811 causes the opening area of the supply port 803 to be varied, and the second land portion 812 causes the opening area of the drainage port 805 to be varied. The opening of the communication port 804 is not closed by either land portion. The space 807 forms a passage for working oil. Moving the spool 81 switches between establishing and shutting off of the connection between the communication passage 434 and the supply passage 433, or switches between establishing and shutting off of the connection between the communication passage 434 and the drainage passage 435. In performing switching, it is assumed as a basic mode that the communication passage 434 communicates with both of the supply passage 433 and the drainage passage 435. To be more specific, in a state where the first land portion 811 partially closes the opening of the supply port 803 which is open to the space 807, the second land portion 812 causes the drainage port 805 to be open to the space 807. In a state where the second land portion 812 partially closes the opening of the drainage port 805 which is open to the space 807, the first land portion 811 causes the supply port 803 to be open to the space 807. The opening of the communication port 804, which is open to the space 807, is always fully open. In performing switching, it is sufficient to have a state where the supply port 803 and the drainage port 805 are simultaneously open to the space 807 (temporarily at a predetermined position of the spool 81). It is not necessary to have a state where the maximum opening area of the supply port 803, which is open to the space 807, and the maximum opening area of the drainage port 805, which is open to the space 807, are equal to each other. Further, it is not necessary that the position of the spool at which the opening area of the supply port 803, which is open to the space 807, starts to decrease be to the same as the position of the spool at which the drainage port 805 starts to become open to the space 807. It is not also necessary that the position of the spool at which the opening area of the drainage port 805, which is open to the space 807, starts to decrease be to the same as the position of the spool at which the supply port 803 starts to become open to the space 807. These cases are determined by tuning.

The spool 81 switches the connection state of the passage, thus switching between establishing and shutting off of the communication between the discharge opening 203 and the second control chamber 292 (through the communication passage 434 and the supply passage 433) and, switching between establishing and shutting off of the communication between the second control chamber 292 and the oil pan 400 (through the communication passage 434 and the drainage passage 435). As shown in FIG. 4, when the spool 81 is at an initial position, the communication passage 434 and the supply passage 433 are connected with each other without any limitation (with the maximum cross-sectional area of the flow passage). The discharge opening 203 and the second control chamber 292 are in a state of maximum communication with each other so that the amount of working oil which is discharged from the discharge opening 203 and may be introduced into the second control chamber 292 becomes the maximum. Further, the communication passage 434 and the drainage passage 435 are connected with each other with the maximum limitation (with the minimum cross-sectional area of the flow passage). The second control chamber 292 and the oil pan 400 are in a state of minimum communication with each other so that the amount of working oil which may be drained from the inside of the second control chamber 29 becomes the minimum. To be more specific, both passages 434, 435 are shut off so that the second control chamber 292 and the oil pan 400 are in a state of non-communication with each other whereby working oil is not drained from the inside of the second control chamber 29. Hereinafter, such a state is referred to as “first state.” As shown in FIG. 5, when the spool 81 slightly moves to the other side in the axial direction from the initial position, the communication passage 434 and the drainage passage 435 are connected with each other with a limitation (with a cross-sectional area of the flow passage which is below maximum). The second control chamber 292 and the oil pan 400 are brought into a state of partially communicating with each other so that working oil may be drained from the inside of the second control chamber 292. Further, the communication passage 434 and the supply passage 433 are connected with each other with a limitation. The discharge opening 203 and the second control chamber 292 are in a state of partially communicating with each other so that working oil discharged from the discharge opening 203 may be introduced into the second control chamber 292. Hereinafter, such a state is referred to as “second state.”

As shown in FIG. 6, when the spool 81 moves from the initial position to the other side in the axial direction by a distance larger than the distance for the second state, the communication passage 434 and the drainage passage 435 are connected with each other with a smaller limitation. The second control chamber 292 and the oil pan 400 are brought into a state of communicating with each other with a larger cross-sectional area of the flow passage so that the amount of working oil which may be drained from the inside of the second control chamber 292 increases. Further, the communication passage 434 and the supply passage 433 are connected with each other with a larger limitation. The discharge opening 203 and the second control chamber 292 are brought into a state of communicating with each other with a smaller cross-sectional area of the flow passage so that the amount of working oil which is discharged from the discharge opening 203 and may be introduced into the second control chamber 292 decrease. Hereinafter, such a state is referred to as “third state.” When the spool 81 moves from the initial position to the other side in the axial direction by a predetermined distance or more, the communication passage 434 and the drainage passage 435 are connected with each other without any limitation. The second control chamber 292 and the oil pan 400 are brought into a state of maximum communication with each other so that the amount of working oil which may be drained from the inside of the second control chamber 292 becomes the maximum. Further, the communication passage 434 and the supply passage 433 are connected with each other with the maximum limitation. The discharge opening 203 and the second control chamber 292 are in a state of minimum communication with each other so that the amount of working oil which is discharged from the discharge opening 203 and may be introduced into the second control chamber 292 becomes the minimum. To be more specific, both passages 433, 434 are shut off so that the discharge opening 203 and the second control chamber 292 are in a state of non-communication with each other whereby working oil is not introduced into the second control chamber 29. Hereinafter, such a state is referred to as “fourth state.”

The solenoid portion 9 can move the spool 81 to any position in response to a control signal (duty ratio D). The position of the spool 81 is proportional to a duty ratio D on average. The control valve 7 functions as a proportional control valve. The control valve 7 can continuously change the position of the spool 81, and can also stop the spool 81 at any position. The position of the spool 81 in the axial direction with respect to the cylinder 80 is mainly determined by a spring force fs and an electromagnetic force fm. The solenoid can continuously change an electromagnetic force fm. Changing the magnitude of electromagnetic force fm allows the spool 81 to move, in other words, allows a transition between the above-mentioned states (state transition). When an electromagnetic force fm becomes larger than a spring force fs, the spool 81 moves to the other side in the axial direction, thus realizing a state transition from the first state toward the fourth state. When an electromagnetic force fm becomes smaller than a spring force fs, the spool 81 moves to one side in the axial direction, thus realizing a state transition from the fourth state toward the first state. An electromagnetic force fm varies according to a duty ratio D. The solenoid functions as a proportional electromagnet which can continuously control an electromagnetic force fm according to a duty ratio D (current value). Basically, an electromagnetic force fm increases when a duty ratio D is increased. The position of the spool 81 (land portions 811, 812) is determined according to a duty ratio D. As shown in FIG. 7, the opening area Si of the supply port 803, which is open to the space 807, and the opening area Sd of the drainage port 805, which is open to the space 807, are respectively proportional to a duty ratio D. When a duty ratio D is less than a predetermined value Ds, the opening area Si assumes the maximum value Smax regardless of the magnitude of the duty ratio D. When a duty ratio D is equal to or more than the predetermined value Ds and less than a predetermined value De, the opening area Si varies according to the duty ratio D so that the opening area Si becomes smaller with a corresponding larger duty ratio D. When a duty ratio D is equal to or more than the predetermined value De, the opening area Si assumes the minimum value Smin (zero in this embodiment) regardless of the magnitude of the duty ratio D. When a duty ratio D is less than the predetermined value Ds, the opening area Sd assumes the minimum value Smin (zero in this embodiment) regardless of the magnitude of the duty ratio D. When a duty ratio D is equal to or more than the predetermined value Ds and less than the predetermined value De, the opening area Sd varies according to the duty ratio D so that the opening area Sd becomes larger with a corresponding larger duty ratio D. When a duty ratio D is equal to or more than the predetermined value De, the opening area Sd assumes the maximum value Smax regardless of the magnitude of the duty ratio D. Respective values of the predetermined value Ds, the predetermined value De, the minimum value Smin, and the maximum value Smax associated with the opening area Si may be different from the respective values associated with the opening area Sd. A predetermined value De at which an opening area Si assumes the minimum value Smin is larger than the predetermined value Ds at which an opening area Sd assumes the minimum value Smin. That is, an opening area Si and an opening area Sd intersect with each other between the predetermined value Ds and the predetermined value De.

The description is made with respect to the operation of the control valve 7 according to the variation in thrust fm of the solenoid (duty ratio D) and the operation of the cam ring 24 which is caused with this operation of the control valve 7. In FIG. 4 to FIG. 6, a spring force fs acts on the spool 81 in the leftward direction, and a thrust fm acts on the spool 81 in the rightward direction. When a duty ratio D is less than the predetermined value Ds, and a thrust fm is equal to or less than a spring force fs (set load of the spring 82), as shown in FIG. 4, the spool 81 is at an initial position where the spool 81 is moved to the position closest to one side in the axial direction. The opening area Si of the supply port 803, which is open to the space 807, assumes the set maximum value Smax. On the other hand, the opening of the drainage port 805, which is open to the space 807, is completely closed by the second land portion 812 so that the opening area Sd assumes the set minimum value Smin (zero). The hydraulic pressure P introduced into the space 807 from the supply passage 433 is introduced into the second control chamber 292 without a pressure loss. The space 807 functions as a communication chamber where working oil flows through. The sum of hydraulic pressure force Fp2 and biasing force Fs (Fp2+Fs (the set load of the spring 25)) is larger than the hydraulic pressure force Fp1 which acts on the cam ring 24. Accordingly, the cam ring 24 is at a position where the cam ring 24 oscillates the most to one side in the rotational direction, thus maintaining the maximum amount of eccentricity Δ.

When a duty ratio D is equal to or more than the predetermined value Ds and less than the predetermined value De, and a thrust fm is larger than a spring force fs (set load of the spring 82), as shown in FIG. 5, the spool 81 slightly moves to the other side in the axial direction from the initial position. The opening of the supply port 803, which is open to the space 807, is partially closed by the first land portion 811 so that the opening area Si becomes smaller than the maximum value Smax. On the other hand, the second land portion 812 also moves and hence, the drainage port 805 becomes partially open to the space 807 whereby the opening area Sd becomes larger than the minimum value Smin (zero). That is, connection destination of the communication passage 434 (second control chamber 292) is switched from only the supply port 803 to both of the supply port 803 and the drainage port 805. Working oil is drained from the space 807 through the drainage passage 435. Accordingly, working oil may be drained from the communication passage 434 (second control chamber 292) via the space 807. Further, working oil may also be drained from the supply passage 433 via the space 807, thus generating a flow of working oil toward the space 807 from the supply passage 433 through the supply port 803. In this flow, the supply port 803 with the decreased opening area Si functions as an orifice so that a hydraulic pressure in the space 807 becomes lower than a hydraulic pressure P in the supply passage 433. Accordingly, a pressure which is reduced to a value lower than the hydraulic pressure P is introduced into the second control chamber 292 from the space 807 and hence, a control hydraulic pressure p drops. The sum of force Fp2 and biasing force Fs (Fp2+Fs) which act on the cam ring 24 becomes smaller than a force Fp1 and hence, the cam ring 24 oscillates to the other side in the rotational direction so that the amount of eccentricity Δ decreases. When the amount of eccentricity Δ (capacity) decreases, a discharge flow rate decreases so that a main gallery hydraulic pressure P drops.

When a duty ratio D further increases in a range where the duty ratio D is less than the predetermined value De, a thrust fm further increases so that, as shown in FIG. 6, the spool 81 further moves to the other side in the axial direction. The opening area Si further decreases, thus approximating the minimum value Smin. On the other hand, the opening area Sd further increases, thus approximating the maximum value Smax. An increase in the opening area Sd increases the amount of working oil drained from the space 807 through the drainage passage 435. Accordingly, the amount of working oil which may be drained from the communication passage 434 (second control chamber 292) via the space 807 increases. Further, a decrease in the opening area Si causes the orifice diameter of the supply port 803 to decrease so that a hydraulic pressure in the space 807 becomes further lower than a hydraulic pressure P in the supply passage 433. Accordingly, a control hydraulic pressure p further drops. The sum of force Fp2 and biasing force Fs (Fp2+Fs) which act on the cam ring 24 further decreases so that an amount of eccentricity Δ further decreases.

As described above, the control valve 7 changes a control hydraulic pressure p and an amount of eccentricity Δ (capacity) by changing the position of the spool 81 according to a duty ratio D. With such a change, the control valve 7 can control a hydraulic pressure P and a discharge flow rate. As shown in FIG. 8, when a duty ratio D is less than the predetermined value Ds, a control hydraulic pressure p assumes the maximum value pmax (which corresponds to a main gallery hydraulic pressure P) regardless of the magnitude of the duty ratio D. When a duty ratio D is equal to or more than the predetermined value Ds and less than the predetermined value De, a control hydraulic pressure p varies according to the duty ratio D so that the control hydraulic pressure p becomes smaller with a corresponding larger duty ratio D. When a duty ratio D is equal to or more than the predetermined value De, a control hydraulic pressure p assumes the minimum value pmin regardless of the magnitude of the duty ratio D. As shown in FIG. 9, when a duty ratio D is less than the predetermined value Ds, an amount of eccentricity Δ assumes the maximum value Δmax regardless of the magnitude of the duty ratio D. When a duty ratio D is equal to or more than the predetermined value Ds and less than the predetermined value De, an amount of eccentricity Δ varies according to the duty ratio D so that the amount of eccentricity Δ becomes smaller with a corresponding larger duty ratio D. When a duty ratio D is equal to or more than the predetermined value De, an amount of eccentricity Δ assumes the minimum value Δmin regardless of the magnitude of the duty ratio D. As shown in FIG. 10, when a duty ratio D is less than the predetermined value Ds, a main gallery hydraulic pressure P assumes the maximum value Pmax (with an engine speed Ne at that time) regardless of the magnitude of the duty ratio D. When a duty ratio D is equal to or more than the predetermined value Ds and less than the predetermined value De, a main gallery hydraulic pressure P varies according to the duty ratio D so that the main gallery hydraulic pressure P becomes smaller with a corresponding larger duty ratio D. When a duty ratio D is equal to or more than the predetermined value De, a main gallery hydraulic pressure P assumes the minimum value Pmin (with an engine speed Ne at that time) regardless of the magnitude of the duty ratio D.

The ECU 6 causes a duty ratio D to be varied according to the stored map such that, within a range where an engine speed Ne is equal to or more than Ne1, the difference ΔP between the detected value and a required value P* for the main gallery hydraulic pressure P falls within a predetermined range. With such a variation, it is possible to realize a characteristic of a hydraulic pressure P with respect to an engine speed Ne as indicated by a bold solid line in FIG. 11. The description is made by taking a low rotational speed range of an engine as an example. As shown in FIG. 12, the ECU 6 causes a duty ratio D to assume 0% (an electric current is not supplied to the solenoid) within a range where an engine speed Ne is less than Ne1. Working oil discharged from the discharge opening 203 is introduced into the second control chamber 292. However, working oil is not drained from the second control chamber 292 to the oil pan 400. Accordingly, working oil can be discharged from the discharge opening 203 in a state where an amount of eccentricity Δ assumes the maximum value Δmax. A main gallery hydraulic pressure P (discharge flow rate) varies according to an engine speed Ne at a constant gradient which corresponds to the maximum capacity. Therefore, after the engine is started, it is possible to cause a main gallery hydraulic pressure P to rapidly rise (it is possible to ensure operational responsiveness of the variable valve device, for example) according to an increase in the engine speed Ne. In a range where an engine speed Ne is equal to or more than Ne1 and less than Ne2, the magnitude of the difference ΔP is larger than a value ΔPset so that the ECU 6 causes a duty ratio D to increase according to an increase in the engine speed Ne. The amount of eccentricity Δ (capacity) decreases according to an increase in the duty ratio D. An increase in the main gallery hydraulic pressure P caused by an increase in the engine speed Ne is suppressed by a decrease in the amount of eccentricity Δ. In the same manner, by causing a duty ratio D to decrease corresponding to a decrease in the engine speed Ne, a decrease in the main gallery hydraulic pressure P can be suppressed by an increase in the amount of eccentricity Δ. Accordingly, a main gallery hydraulic pressure P is maintained (controlled at a fixed value) at P1 or around P1 regardless of engine speed Ne. Therefore, it is possible to decrease the difference ΔP by making a main gallery hydraulic pressure P approximate a required value P*. As described above, in the case where an engine speed Ne is equal to or more than Ne1, when the difference ΔP is larger than a value ΔPset, the ECU 6 causes an amount of working oil which is drained from the second control chamber 292 to the oil pan 400 to be varied while allowing working oil to be introduced into the second control chamber 292 until the difference ΔP becomes equal to or less than a value ΔPset. In a range where an engine speed Ne is equal to or more than Ne2 and less than Ne3, the magnitude of the difference ΔP is equal to or less than a value ΔPset and hence, the ECU 6 maintains a duty ratio D at D3 (which is a value immediately before a value at which the magnitude of the difference ΔP becomes equal to or less than the value ΔPset). A main gallery hydraulic pressure P varies according to the engine speed Ne at a constant gradient corresponding to a capacity which corresponds to D3. A main gallery hydraulic pressure P rises (drops) corresponding to an increase (decrease) in engine speed Ne. In a range where an engine speed Ne is equal to or more than Ne3, the magnitude of the difference ΔP is larger than a value ΔPset and hence, in the same manner as the range where an engine speed Ne is equal to or more than Ne1 and less than Ne2, the ECU 6 causes a duty ratio D to increase (decrease) according to an increase (decrease) in the engine speed Ne. Accordingly, a main gallery hydraulic pressure P is maintained (controlled at a fixed value) at P2 or around P2 regardless of engine speed Ne. This operation is repeated plurality of times according to variation in engine speed Ne, thus realizing the above-mentioned characteristic having a stairs-like shape.

The solenoid can change, according to duty ratio D (the value of an electric current supplied), the magnitude of an electromagnetic force fm which biases the spool 81 in the axial direction. Accordingly, varying duty ratio D according to engine speed Ne allows main gallery hydraulic pressure P and discharge flow rate to be freely varied (controlled). Characteristics of main gallery hydraulic pressure P and discharge flow rate with respect to engine speed Ne can be easily caused to approximate desired characteristics. Accordingly, power loss caused due to unnecessary rise in discharge pressure (increase in flow rate) can be suppressed so that fuel economy can be improved. In the above-mentioned description, characteristic is described to have a stairs-like shape for facilitating understanding of the description. However, in an actual control, numerous number of stairs may be formed, that is, main gallery hydraulic pressure P may be steplessly controlled according to an engine speed Ne, thus approximately continuously controlling the main gallery hydraulic pressure P according to required hydraulic pressure P*. A main gallery hydraulic pressure P is feedback controlled according to a differential pressure ΔP and hence, the control valve 7 and the cam ring 24 are operated such that the characteristic of a discharge pressure P which corresponds to the variation in engine speed Ne approximates a required characteristic. With such feedback control, while the pump 2 is prevented from being affected by leakage (leakage of working oil) or the like caused by a clearance formed between members, the characteristic of a hydraulic pressure P can be accurately controlled. A method for feedback controlling a hydraulic pressure P to a required value P* is not limited to the above-mentioned method, and any method may be adopted. Setting a value ΔPset to a smaller value allows steps of a stairs-like shape to continuously change more finely. A value ΔPset may be set to zero. Hunting in control can be suppressed by setting a value ΔPset to a value other than zero, and by preventing a duty ratio D from being varied when the magnitude of difference ΔP is equal to or less than the value ΔPset.

The control valve 7 can continuously change the position of the spool 81. Accordingly, the control valve 7 can move the spool 81 to any position, thus controlling a control hydraulic pressure p, an amount of eccentricity Δ (capacity), and a main gallery hydraulic pressure P to any values. The control valve 7 can stop the spool 81 at any position. Accordingly, the control valve 7 can fix the spool 81 at any position, thus fixing a control hydraulic pressure p and an amount of eccentricity Δ (capacity) at any values. Therefore, the control valve 7 can realize control to fix a gradient when a hydraulic pressure P rises or drops according to a variation in engine speed Ne.

The control valve 7 includes the solenoid portion 9 which is capable of generating an electromagnetic force fm for biasing the spool 81. Accordingly, the spool 81 can be moved to any position by the solenoid portion 9. The spool 81 is integrally coupled with the plunger of the solenoid portion 9. Therefore, even if a force generated by a hydraulic pressure acts on the spool 81 from one side or the other side in the axial direction, it is possible to prevent the spool 81 from being moved. With such a configuration, a control hydraulic pressure p, an amount of eccentricity Δ, and a hydraulic pressure P are prevented from being easily affected by disturbances and hence, ease of control can be improved. A control hydraulic pressure p, an amount of eccentricity Δ, and a hydraulic pressure P are controlled by opening/closing the port of the control valve 7 and hence, the control is not affected by the spring constant of the spring 25 of the cam ring 24.

The control valve 7 is provided in the second feedback passage 432. With the movement of the spool 81, the control valve 7 varies the cross-sectional area Sd of the flow passage, through which working oil in the second control chamber 292 is drained to the oil pan 400, while making the discharge opening 203 and the second control chamber 292 communicate with each other. By varying the cross-sectional area Sd of the flow passage as described above, the drainage amount of working oil from the space 807 (second control chamber 292) is varied (adjusted). With such variation, a control hydraulic pressure p is varied (controlled), thus controlling the amount of eccentricity Δ (capacity) and a main gallery hydraulic pressure P. In this embodiment, simultaneously with the variation in the cross-sectional area Sd, the discharge opening 203 and the space 807 (second control chamber 292) are made to communicate with each other. Accordingly, the drainage amount of working oil from the second control chamber 292 varies slowly with respect to the movement of the spool 81. Therefore, a control hydraulic pressure p, an amount of eccentricity Δ (capacity), and a main gallery hydraulic pressure P vary slowly with respect to variation in duty ratio D (the movement amount of the spool 81) (the rapid operation of the cam ring 24 is suppressed). As a result, ease of control of a main gallery hydraulic pressure P is improved.

With the movement of the spool 81 to the other side in the axial direction (in the first direction), the control valve 7 increases the cross-sectional area Sd of the flow passage, through which working oil in the second control chamber 292 is drained to the oil pan 400, while decreasing the cross-sectional area Si of the flow passage, through which working oil is introduce from the discharge opening 203 to the second control chamber 292. Accordingly, the discharge opening 203 and the space 807 (second control chamber 292) are made to communicate with each other simultaneously with an increase in the cross-sectional area Sd and hence, a drainage amount from the second control chamber 292 increases slowly with respect to the movement of the spool 81. Accordingly, it is possible to cause the falling gradient of a hydraulic pressure P to slowly decrease with respect to a variation (increase) in duty ratio D. Further, the orifice diameter of the supply port 803 decreases with a decrease in the opening area Si. That is, the supply port 803 functions as a variable orifice. For this reason, it is possible to cause a hydraulic pressure in the space 807 (that is, a control hydraulic pressure p) to drop sufficiently with respect to a hydraulic pressure P in the supply passage 433 without significantly increasing the drainage amount from the space 807. Accordingly, an increase in drainage amount can be suppressed, thus suppressing lowering of efficiency of the pump 2. Further, an opening area Si is decreased in increasing a drainage amount from the second control chamber 292 so that an amount of working oil which can be introduced into the second control chamber 292 decreases. Therefore, it is possible to cause a control hydraulic pressure p to drop sufficiently when desired and hence, a range (lower limit) of a control hydraulic pressure p can be expanded. For this reason, ease of control is improved.

With the movement of the spool 81 to one side in the axial direction (in a second direction), the control valve 7 decreases the cross-sectional area Sd of the flow passage while increasing the cross-sectional area Si of the flow passage. Accordingly, the discharge opening 203 and the space 807 (second control chamber 292) are made to communicate with each other simultaneously with a decrease in the cross-sectional area Sd and hence, a drainage amount from the second control chamber 292 decreases slowly with respect to the movement of the spool 81. Accordingly, it is possible to cause the rising gradient of a hydraulic pressure P to slowly increase with respect to a variation (decrease) in duty ratio D. Further, an opening area Si is increased in decreasing a drainage amount from the second control chamber 292 so that an amount of working oil which can be introduced into the second control chamber 292 increases. Therefore, it is possible to cause a control hydraulic pressure p to sufficiently rise when desired and hence, a range (upper limit) of a control hydraulic pressure p can be expanded. In other words, when the amount of working oil which is discharged from the discharge opening 203 and introduced into the second control chamber 292 increases, a control mechanism 3 decreases the amount of working oil drained from the inside of the second control chamber 292. When the amount of working oil which is discharged from the discharge opening 203 and introduced into the second control chamber 292 decreases, the control mechanism 3 increases the amount of working oil drained from the inside of the second control chamber 292. Accordingly, it becomes possible to vary (control) a control hydraulic pressure p within a wide range from a low pressure to a high pressure. Further, the operation of the cam ring 24 becomes stable so that a discharge pressure P also becomes stable.

To be more specific, the cylinder 80 of the control valve 7 has the supply port 803 as a first port communicating with the discharge opening 203, the communication port 804 as a second port communicating with the second control chamber 292, and the drainage port 805 as a third port communicating with the oil pan 400. These ports 803 to 805 are open on the inner periphery of the cylinder 80. The various ports of the control valve 7 can be formed with a simple configuration described above. It is sufficient for the drainage port 805 to communicate with the low pressure portion. It is not limited to the configuration that the drainage port 805 communicates with the oil pan 400 (atmospheric pressure). For example, the drainage port 805 may communicate with the intake opening 201 side (where an intake negative pressure is generated). The spool 81 of the control valve 7 is movable in the cylinder 80. The spool 81 includes: the first land portion 811 as a first large diameter portion which can vary the area of the above-mentioned opening of the supply port 803; and the second land portion 812 as a second large diameter portion which can vary the area of the above-mentioned opening of the drainage port 805. With such a simple configuration of a spool valve, the valve portion 8 can control a control hydraulic pressure p.

To be more specific, the first land portion 811 and the second land portion 812 are disposed such that the respective ports 803 to 805 can be at least partially open simultaneously on the inner periphery of the spool 81 within a range (space 807) between the first land portion 811 and the second land portion 812. Accordingly, simultaneous with the communication between the supply port 803 (discharge opening 203) and the communication port 804 (second control chamber 292) via the space 807, the communication port 804 (second control chamber 292) and the drainage port 805 (oil pan 400) can be made to communicate with each other. Further, with the movement of the spool 81, the opening area Sd of the drainage port 805 which is open to the space 807 (the cross-sectional area of the flow passage through which working oil in the second control chamber 292 is drained to the oil pan 400) can be varied while the supply port 803 (discharge opening 203) and the communication port 804 (second control chamber 292) are made to communicate with each other. In other words, in a state where a flow of working oil from the supply port 803 to the communication port 804, and a flow of working oil from the communication port 804 to the drainage port 805 are allowed, the first land portion 811 can vary the cross-sectional area of the flow passage between the supply port 803 and the communication port 804. Further, the second land portion 812 can vary the cross-sectional area of the flow passage between the communication port 804 and the drainage port 805. To be more specific, the first land portion 811 can vary the area of the above-mentioned opening of the supply port 803. The second land portion 812 can vary the area of the above-mentioned opening of the drainage port 805. When the first land portion 811 varies the area of the above-mentioned opening of the supply port 803, the second land portion 812 varies the area of the above-mentioned opening of the drainage port 805. With the movement of the spool 81 to one side in the axial direction, the opening area Sd decreases while the opening area Si of the supply port 803 which is open to the space 807 (the cross-sectional area of the flow passage through which working oil is introduced from the discharge opening 203 to the second control chamber 292) increases. With the movement of the spool 81 to the other side in the axial direction, the opening area Sd increases while the opening area Si decreases.

The spool 81 includes the first land portion 811, the second land portion 812, and the connecting portion 813. The connecting portion 813 connects the first land portion 811 and the second land portion 812 with each other. The first land portion 811 is disposed on the supply port 803 side, and is biased to one side in the axial direction by the solenoid portion 9. The second land portion 812 is disposed on the drainage port 805 side, and is biased to the other side in the axial direction by the spring 82. As described above, the spring 82 and the solenoid portion 9 differ from each other in the direction that the member biases the spool 81 and hence, the electromagnetic force fm and the spring force fs act in opposite directions. Accordingly, the solenoid portion 9 can favorably control the spool 81. Further, the spring 82 functions as a return spring for the spool 81 (the plunger of the solenoid portion 9). Also in the case where there is a malfunction in the solenoid portion 9, the spool 81 is biased to the other side in the axial direction (toward the initial position) by the spring 82 so that it is possible to set the amount of eccentricity Δ to the maximum. Therefore, it is possible to cause a discharge pressure P to rise with the maximum gradient according to an increase in the engine speed Ne.

The area of the first region 246 of the outer peripheral surface 245 of the cam ring which faces the first control chamber 291 may be set equal to the area of the second region 246 of the outer peripheral surface 245 of the cam ring which faces the second control chamber 292. Alternatively, the area of the second region 247 may be set smaller than the area of the first region 246. In this embodiment, the area of the second region 247 (pressure receiving area) is larger than the area of the first region 246 (pressure receiving area). Accordingly, during the operation of the pump 2 at a high speed, a stable hydraulic pressure P can be supplied. That is, when an engine speed Ne (pump rotational speed) rises, air bubbles may be generated in working oil. When these air bubbles are collapsed in the working chamber 28 within the discharge region, there is a possibility that a balance of pressure which acts on the cam ring 24 is disturbed so that the behavior of the cam ring 24 becomes unstable, thus causing discharge pressure P to drop. However, even when the pressure in the first control chamber 291 and the pressure in the second control chamber 292 are equal to each other, hydraulic pressure force Fp2 is larger than hydraulic pressure force Fp1. Accordingly, even if a balance of a pressure which acts on the cam ring 24 from the working chamber 28 is disturbed, the cam ring 24 is biased in the direction that an amount of eccentricity Δ increases, thus suppressing that the behavior of the cam ring 24 becomes unstable. Therefore, it is possible to suppress dropping of control hydraulic pressure P so that a stable control hydraulic pressure P can be supplied. In other words, it becomes possible to discharge working oil of high pressure.

The volume of the first control chamber 291 increases with the movement of the cam ring 24 in the direction opposing the biasing force Fs of the spring 25. That is, hydraulic pressure force Fp1 acts in the direction opposite to the direction of biasing force Fs. The volume of the second control chamber 292 increases with the movement of the cam ring 24 in the same direction as biasing force Fs. That is, hydraulic pressure force Fp2 acts in the same direction as biasing force Fs, thus assisting the biasing force Fs. The operation of the cam ring 24 is decided by the magnitude relationship between hydraulic pressure force Fp1 and the sum of hydraulic pressure force Fp2 and biasing force Fs (Fp2+Fs). Accordingly, only a small biasing force Fs is required for causing the cam ring 24 to be operated in the direction that the amount of eccentricity Δ increases. The load of the spring 25 can be reduced. Accordingly, only a small hydraulic pressure force Fp1 is required for causing the cam ring 24 to be operated in the direction that the amount of eccentricity Δ decreases. That is, it is possible to lower a discharge pressure when the cam ring 24 is operated in the direction that the amount of eccentricity Δ decreases. In other words, discharge of a low pressure working oil can be realized. The cam ring 24 can be oscillated about a fulcrum disposed in the pump accommodating chamber 200. Accordingly, a range where the cam ring 24 is operated can be made compact, thus realizing the reduction in size of the pump 2.

Lowering a pressure in the second control chamber 292 increases the difference between the pressure in the second control chamber 292 and the pressure at the discharge port 204. Accordingly, there is a possibility of increase in the amount of working oil to be leaked through a gap formed between the side surface of the cam ring 24 in the axial direction and the bottom surface of the pump accommodating chamber 200. However, the width in the radial direction of the second region 247 of the cam ring 24 is larger than the width in the radial direction of the first region 246. Accordingly, sealing property is improved more on the second control chamber 292 side than on the first control chamber 291 side and hence, the above-mentioned leakage can be suppressed. A discharge pressure is always introduced into the first control chamber 291 so that the difference between the pressure in the first control chamber 291 and the pressure at the discharge port 204 is small. Accordingly, sealing property is improved (the width in the radial direction is increased) only on the second control chamber 292 side and hence, unnecessary increase in weight is suppressed.

Second Embodiment

First, the configuration is described. As shown in FIG. 13, a cylinder 80C has a bottom portion 802 on one side in the axial direction, and the other side of the cylinder 80C in the axial direction is open. The opening of a communication port 804C is formed on an inner peripheral surface 800 of the cylinder between the opening of a supply port 803 and the opening of a drainage port 805. In the axial direction of the cylinder 80C, the size of the above-mentioned opening of the communication port 804C is larger than the sizes of the above-mentioned openings of the supply port 803 and the drainage port 805. A spool 81C includes a first land portion 814, a second land portion 814, and the connecting portion 813. The size of the first land portion 814 in the axial direction is smaller than the size of the above-mentioned opening of the communication port 804C. The first land portion 814 is disposed in a region which overlaps with the communication port 804C in the axial direction of the cylinder 80C, and in the vicinity of such a region. The drainage port 805 is always open to a space 807C, and the communication port 804C may be open to the space 807C. The supply port 803 is always open to a space 808C, and the communication port 804C is open to the space 808C in the initial state.

One end side of a spring 82C is fitted on the outer peripheral side of a projection portion which projects from the first land portion 814 of the spool 81C, and one end of the spring 82C is in contact with the end surface of the first land portion 814 on one side. The other end of the spring 82C is in contact with a bottom portion 802. A spring force fs of the spring 82C biases the first land portion 814 (spool 81C) to the other side in the axial direction. A solenoid portion 9 is joined to the other side of a valve portion 8 in the axial direction, thus closing the opening of the cylinder 80C on the other side in the axial direction. The second land portion 815 of the spool 81C is integrally joined to a plunger. The electromagnetic force fin of the solenoid portion 9 biases the second land portion 815 (the spool 81C and the first land portion 814) to one side in the axial direction. Other configurations are to the same as those in the first embodiment and hence, corresponding constitutional elements are given the same reference numerals, and the repeated description of such constitutional elements is omitted.

Next, the manner of operation is described. The first land portion 814 can vary the opening area of the communication port 804C. When the edge of the first land portion 814 on one side in the axial direction is positioned on the other side in the axial direction of the edge of the communication port 804C on one side in the axial direction, the communication port 804C is at least partially open to the space 808C. The above-mentioned opening of the supply port 803 communicates with the above-mentioned opening of the communication port 804C via the space 808C. The space 808C forms a passage for working oil. When the edge of the first land portion 814 on the other side in the axial direction is positioned on one side in the axial direction of the edge of the communication port 804C on the other side in the axial direction, the communication port 804C is at least partially open to the space 807C. The above-mentioned opening of the drainage port 805 communicates with the above-mentioned opening of the communication port 804C via the space 807C. The space 807C forms a passage for working oil. When the first land portion 814 falls within a range of the communication port 804C in the axial direction, the communication port 804C is open to both sides of the first land portion 814 in the axial direction so that the communication port 804C is partially open to both of the space 807C and the space 808C. The first land portion 814 moves within a range of the communication port 804C in the axial direction, thus varying the area Si of the above-mentioned opening of the communication port 804C, communicating with the above-mentioned opening of the supply port 803, and the area Sd of the above-mentioned opening of the communication port 804C, communicating with the above-mentioned opening of the drainage port 805.

As shown in FIG. 14, when the spool 81C is at the initial position, the first land portion 814 closes the opening of the communication port 804C which is open to the space 807C and, the first land portion 814 causes the communication port 804C to be open to the space 808C, and sets the opening area Si of the communication port 804C to the maximum Smax. A first state similar to a state shown in FIG. 4 is realized so that the maximum amount of eccentricity Δ is maintained. As shown in FIG. 15, when the spool 81C slightly moves to one side in the axial direction from the initial position, the first land portion 814 causes the communication port 804C to become open to the space 808C and, causes the communication port 804C to become open to the space 807C. A second state similar to a state shown in FIG. 5 is realized. The opening area Si becomes smaller than the maximum value Smax. Working oil may be drained from the communication passage 434 (second control chamber 292) via the space 807C. Working oil may also be drained from the communication port 804C via the space 807C, thus generating a flow of working oil toward the space 807C from a supply passage 433 (space 808C) through the communication port 804C. In this flow, the communication port 804C with the decreased opening area Si functions as an orifice so that a hydraulic pressure in the communication passage 434 (communication port 804C) becomes lower than a hydraulic pressure P in the supply passage 43 (space 808C). Accordingly, a control hydraulic pressure p introduced into the second control chamber 292 drops so that the amount of eccentricity Δ decreases. As shown in FIG. 16, when the spool 81C moves from the initial position to one side in the axial direction by a distance larger than a distance for the second state (FIG. 15), the first land portion 814 increases the opening area Sd of the communication port 804C, which is open to the space 807C, and the first land portion 814 decreases the opening area Si of the communication port 804C, which is open to the space 808C. A third state similar to a state shown in FIG. 6 is realized. An increase in the opening area Sd increases the amount of working oil drained from the space 807C through the drainage passage 435. Accordingly, the amount of working oil which may be drained from the communication passage 434 (second control chamber 292) via the space 807C increases. Further, a decrease in the opening area Si decreases the orifice diameter of the communication port 804C so that a hydraulic pressure in the communication passage 434 becomes further lower than a hydraulic pressure P in the supply passage 433. Accordingly, a control hydraulic pressure p further drops so that the amount of eccentricity Δ further decreases.

In FIG. 14 to FIG. 16, a spring force fs acts on the spool 81C in the rightward direction, and an electromagnetic force fm acts on the spool 81C in the leftward direction. When an electromagnetic force fin becomes larger than a spring force fs, the spool 81C moves to one side in the axial direction, thus realizing a state transition from the first state toward the third state. When an electromagnetic force fm becomes smaller than a spring force fs, the spool 81C moves to the other side in the axial direction, thus realizing a state transition from the third state toward the first state.

Varying the cross-sectional area Sd of the flow passage allows the drainage amount of working oil from the communication port 804C (second control chamber 292) to be varied (adjusted). With such variation, a control hydraulic pressure p is varied (controlled). In this embodiment, simultaneous with the variation in the cross-sectional area Sd, the discharge opening 203 and the communication port 804C (second control chamber 292) are made to communicate with each other. Accordingly, the drainage amount of working oil from the second control chamber 292 varies slowly with respect to the movement of the spool 81C. With the movement of the spool 81C to one side in the axial direction, the control valve 7 increases the cross-sectional area Sd of the flow passage, through which working oil in the second control chamber 292 is drained to the oil pan 400, while decreasing the cross-sectional area Si of the flow passage, through which working oil is introduced from the discharge opening 203 to the second control chamber 292. With the movement of the spool 81C to the other side in the axial direction, the cross-sectional area Sd of the flow passage is decreased while the cross-sectional area Si of the flow passage is increased.

To be more specific, the opening of the communication port 804C (second port) is formed on the inner peripheral surface 800 of the cylinder between the opening of the supply port 803 (first port) and the opening of the drainage port 805 (third port). The spool 81C includes the first land portion 814 which is biased to one side by the solenoid portion 9 and, is biased to the other side by the spring 82C. The first land portion 814 varies the area Si of the above-mentioned opening of the communication port 804C communicating with the above-mentioned opening of the supply port 803, and the area Sd of the above-mentioned opening of the communication port 804C communicating with the above-mentioned opening of the drainage port 805. Accordingly, with such a simpler configuration of a spool valve, the valve portion 8 can control a control hydraulic pressure p. The manner of other operations and advantageous effects are the same as those in the first embodiment. The configuration of this embodiment is also applicable to any embodiment other than the first embodiment.

Third Embodiment

First, the configuration is described. As shown in FIG. 17, a pump 2 is configured such that, a cam ring 24A of the pump 2 moves in a slidable manner. The pump 2 does not include the first sealing member 261, the second sealing member 262, and the pin 27 in the first embodiment. The inner peripheral surface of a pump accommodating chamber 200A of a housing body 20A has planar surfaces 205 to 207. These planar surfaces 205 to 207 expand parallel to an axis 22AP of a rotor 22A. The planar surfaces 205, 206 are parallel to each other, and the planar surface 207 expands in a direction orthogonal to these planar surfaces 205, 206. The outer periphery of the cam ring 24A has four protrusions 246 to 249 which protrude outward in the radial direction. The first protrusion 246 and the second protrusion 247 are disposed on sides opposite to each other with respect to an axis 24AP of an inner peripheral surface 240A of the cam ring, and the third protrusion 248 and the fourth protrusion 249 are disposed on sides opposite to each other with respect to the axis 24AP. The first protrusion 247, the second protrusion 247, and the third protrusion 248 have planar surfaces, and these planar surfaces expand parallel to the axis 24AP. The planar surface of the first protrusion 246 and the planar surface of the second protrusion 247 are parallel to each other. A distance between both planar surfaces is slightly shorter than a distance between the planar surfaces 205, 206 of the housing body 20A. The planar surface of the first protrusion 246 and the planar surface of the second protrusion 247 respectively oppose the planar surfaces 205, 206. The planar surface of the third protrusion 248 expands in a direction orthogonal to the planar surface of the first protrusion 247 (second protrusion 247), and opposes the planar surface 207 of the inner peripheral surface of the pump accommodating chamber 200A. One end of a spring 25A is mounted on the fourth protrusion 249.

A first control chamber 291A is formed of a space defined between a portion of an outer peripheral surface 245A of the cam ring ranging from the first protrusion 246 to the second protrusion 247 via the third protrusion 248 and the inner peripheral surface of the pump accommodating chamber 200A. A second control chamber 292A is formed of a space defined between a portion of the outer peripheral surface 245A of the cam ring ranging from the first protrusion 246 to the second protrusion 247 via the fourth protrusion 249 and the inner peripheral surface of the pump accommodating chamber 200A. A spring accommodating chamber 293A is integrally formed with the second control chamber 292A, and has a bottomed cylindrical shape. The other end side of the spring 25A is disposed in the spring accommodating chamber 293A. A gap formed between the planar surface of the first protrusion 246 and the planar surface 205 of the pump accommodating chamber 200A, and a gap formed between the planar surface of the second protrusion 247 and the planar surface 206 of the pump accommodating chamber 200A are small and hence, sealing is provided between the first control chamber 291A and the second control chamber 292A (spring accommodating chamber 293A).

The control valve 7 is configured such that, as shown in FIG. 18, the valve portion 8 includes a retainer 83, and a stopper 84. The solenoid portion 9 includes a rod 91. The rod 91 is joined to a plunger. The inner peripheral surface 800 of a cylinder 80A has a cylindrical shape, and both ends of the cylinder 80A in the axial direction are open. The retainer 83 has a bottomed cylindrical shape, and has a hole 830 in a bottom portion 831. The retainer 83 is disposed at the end of the cylinder 80A on the other side in the axial direction. A cylindrical portion 832 of the retainer 83 is fitted in the inner periphery of the cylinder 80A. The stopper 84 has an annular shape, and has a hole 840 at a center portion thereof. The stopper 84 is disposed at the end of the cylinder 80A on the other side in the axial direction, and partially closes the opening of the cylinder 80A. The surface of the stopper 84 on one side in the axial direction opposes the bottom portion 831 of the retainer 83. One end of the rod 91 projects to the inner peripheral side of the cylinder 80A, and is joined to the end of a spool 81A (first land portion 811A) on the other side in the axial direction. The rod 91 functions as a member for allowing the solenoid to bias the spool 81A in the axial direction. The rod 91 is integrally formed with the spool 81A (is not separate from the spool 81A). A space 808A is defined between a second land portion 812A and the retainer 83 in the cylinder 80A. One end side of a spring 82A is fitted in the inner peripheral side of the retainer 83, and one end of the spring 82A is in contact with the bottom portion 831 of the retainer 83. The other end of the spring 82A is in contact with the end surface of the spool 81A (second land portion 812A) on one side in the axial direction. Other configurations are to the same as those in the first embodiment and hence, corresponding constitutional elements are given the same reference numerals, and the repeated description of such constitutional elements is omitted.

Next, the manner of operation is described. The rotor 22A rotates in the clockwise direction in FIG. 17. The cam ring 24A can slidably move (linearly move in the radial direction of the rotor 22) along the planar surfaces 205, 206 in the pump accommodating chamber 200A. The planar surfaces 205, 206 are disposed in the pump accommodating chamber 200A, and function as guide portions (guides) for the above-mentioned movement. With a translational motion of the cam ring 24A, the difference (amount of eccentricity Δ) between the axis (center of rotation) 22AP of the rotor 22A and the axis (center) 24AP of the inner peripheral surface 240A of the cam ring varies. The volume of the first control chamber 291A and the volume of the second control chamber 292A are variable with the movement of the cam ring 24A. The position of the cam ring 24A (amount of eccentricity Δ) is determined by a force Fp1 caused by a pressure in the first control chamber 291A, a force Fp2 caused by a pressure in the second control chamber 292A, and a biasing force Fs of the spring 25A. When a force Fp1 becomes larger than the sum of force Fp2 and biasing force Fs (Fp2+Fs), the cam ring 24A moves to the side where an amount of eccentricity Δ (capacity) reduces. When a force Fp1 becomes smaller than the sum of force Fp2 and biasing force Fs (Fp2+Fs), the cam ring 24A moves to the side where an amount of eccentricity Δ (capacity) increases. When an electromagnetic force fm is equal to or less than a spring force fs, as shown in FIG. 19, in the same manner as FIG. 4, the spool 81A is at the initial position, and a supply port 803A communicates with a communication port 804A. The amount of eccentricity Δ becomes the maximum due to working oil (control hydraulic pressure pmax) introduced into a second control chamber 292A. When an electromagnetic force fm is larger than a spring force fs, in the same manner as FIG. 5 and FIG. 6, the spool 81 moves to the other side in the axial direction from the initial position so that a drainage port 805A communicates with the communication port 804A (as well as the supply port 803A). Working oil is drained from the second control chamber 292A and hence, an amount of eccentricity Δ decreases. As described above, the configuration is adopted where the amount of eccentricity Δ (capacity) varies with a translational motion of the cam ring 24A and hence, configurations of the respective control chambers 291A, 292A can be simplified. The manner of other operations and advantageous effects are to the same as those in the first embodiment. The configuration of this embodiment is also applicable to an embodiment other than the first embodiment.

Fourth Embodiment

First, the configuration is described. A pump 2 is configured such that, as shown in FIG. 20, as viewed in the axial direction of a cam ring 24B, a first protrusion 241B and a second protrusion 242B are disposed on the same side with respect to a straight line passing through the axis of a pin 27B and a center 24BP of an inner peripheral surface 240B of the cam ring. The first protrusion 241B is disposed between the second protrusion 242B and a third protrusion 243B (pin 27B). The first protrusion 241B and the second protrusion 242B are disposed on the side opposite to a fourth protrusion 244B with respect to the above-mentioned straight line. A first control chamber 291B is formed of a space defined between a portion of an outer peripheral surface 245B of the cam ring ranging from the first protrusion 241B (first sealing member 261B) to the third protrusion 243B (pin 27B) and the inner peripheral surface of a pump accommodating chamber 200B. (A portion of) a discharge port 204B and a discharge opening 203B are open on the bottom surface of the pump accommodating chamber 200B which faces the first control chamber 291B. A second control chamber 292B is formed of a space defined between a portion of the outer peripheral surface 245B of the cam ring ranging from the first protrusion 241B (first sealing member 261B) to the second protrusion 242B (second sealing member 262B) and the inner peripheral surface of the pump accommodating chamber 200B. A second region 247B of the outer peripheral surface 245B of the cam ring between the first sealing member 261B and the second sealing member 262B faces the second control chamber 292. The second control chamber 292B is sealed by the first sealing member 261B and the second sealing member 262B. The other end of a communication passage 434 is open on the bottom surface of the pump accommodating chamber 200B which faces the second control chamber 292B. A spring accommodating chamber 293B is formed of a space defined between a portion of the outer peripheral surface 245B of the cam ring ranging from the third protrusion 243B (pin 27B) to the second protrusion 242B (second sealing member 262B) via the fourth protrusion 244B and the inner peripheral surface of the pump accommodating chamber 200B. (A portion of) an intake port 202B and an intake opening 201B are open on the bottom surface of the pump accommodating chamber 200B which faces the spring accommodating chamber 293B. The discharge port 204B communicates with both of a working chamber 28B and the first control chamber 291B, thus functioning as a first feedback passage 431.

The control valve 7 is configured such that, as shown in FIG. 21, the end portion of a cylinder 80B on one side in the axial direction is not open, but is closed. One end of the spring 82 is in contact with the above-mentioned end portion of the cylinder 80B. The cylinder 80B has a second drainage port 806 which penetrates the cylinder 80B in a radial direction. A drainage port 805B, a communication port 804B, a supply port 803B, and the second drainage port 806 are arranged in this order from one side to the other side in the axial direction of the cylinder 80B. The drainage port 805B is open to a space 807B in an initial state. The communication port 804B is always open to the space 807B, and the supply port 803B may be open to the space 807B. In the inside of the cylinder 80B, a space 808 is defined between a second land portion 812B and the end portion of the cylinder 80B on other side in the axial direction. The supply port 803B is open to the space 808 in an initial state, and the second drainage port 806 is always open to the space 808. The second drainage port 806 communicates with an oil pan 400 through a drainage passage 435. Other configurations are to the same as those in the first embodiment and hence, corresponding constitutional elements are given the same reference numerals, and the repeated description of such constitutional elements is omitted.

Next, the manner of operation is described. A rotor 22B rotates in the clockwise direction in FIG. 20. The cam ring 24B is biased by a spring force Fs of a spring 25 to one side in the rotational direction about the pin 27B (to the side where the amount of increase or decrease in volume of each of the plurality of working chambers 28B increases, and the amount of eccentricity Δ increases). The cam ring 24B is biased to the other side in the rotational direction about the pin 27B (to the side where the amount of increase or decrease in volume of each of the plurality of working chambers 28B decreases, and the amount of eccentricity Δ decreases) by a force Fp1 which is received by a first region 246B of the outer peripheral surface 245B, and which is caused by a hydraulic pressure P in the first control chamber 291B, and by a force Fp2 which is received by the second region 247B, and which is caused by a hydraulic pressure P in the second control chamber 292B. The volume of the first control chamber 291B and the volume of the second control chamber 292B increase with the movement of the cam ring 24B to the other side in the above-mentioned rotational direction (in the direction opposite to the direction of a spring force Fs). When the sum of force Fp1 and force Fp2 (Fp1+Fp2) becomes larger than a spring force Fs, the cam ring 24B oscillates to the other side in the above-mentioned rotational direction and hence, an amount of eccentricity Δ (capacity) reduces. When the sum of force Fp1 and force Fp2 (Fp1+Fp2) becomes smaller than a spring force Fs, the cam ring 24B oscillates to one side in the rotational direction about the pin 27B (to the side where the amount of eccentricity Δ increases) and hence, capacity increases.

A first land portion 811B of a spool 81B varies the opening area of the drainage port 805B, and a second land portion 812B varies the opening area of the supply port 803B. When an electromagnetic force fm is equal to or less than a spring force fs (set load of a spring 82B), as shown in FIG. 22, the spool 81B is at the initial position and, in a state where the second land portion 812 closes the opening of the supply port 803B which is open to a space 807B, the first land portion 811B causes the drainage port 805B to become open to the space 807B. The drainage port 805B communicates with the communication port 804B. Working oil is drained from a second control chamber 292B so that a force Fp2 decreases. When the sum of force Fp1 and force Fp2 (Fp1+Fp2) is smaller than a biasing force Fs (set load of the spring 25), an amount of eccentricity Δ becomes the maximum. Working oil is drained from the space 808 through the second drainage port 806 and hence, the space 808 is maintained at a low pressure. When an electromagnetic force fm becomes larger than a spring force fs, the spool 81B moves to the other side in the axial direction from the initial position. In a state where the first land portion 811B partially closes the opening of the drainage port 805B which is open to the space 807B, the second land portion 812B causes the supply port 803B to be partially open to the space 807B. The supply port 803B communicates with the communication port 804B. The communication passage 434 and the supply passage 433 are connected with each other so that working oil discharged from a discharge opening 203B is introduced into the second control chamber 292B. A force Fp2 increases due to a hydraulic pressure p introduced into the second control chamber 292B. When the sum of force Fp1 and force Fp2 (Fp1+Fp2) becomes larger than a biasing force Fs, an amount of eccentricity Δ decreases.

As described above, the present invention is applicable to the pump 2 having the configuration where the volumes of the first control chamber 291B and the second control chamber 292B increase (a pressure in the second control chamber 292B acts in a direction that an amount of eccentricity Δ is reduced) with the movement of the cam ring 24B in the direction opposing the biasing force Fs of a spring 25B. The characteristic of main gallery hydraulic pressure P with respect to engine speed Ne can be easily caused to approximate the desired characteristic. Additionally, ease of control can be improved. The manner of other operations and advantageous effects are to the same as those in the first embodiment. The configuration of this embodiment is also applicable to an embodiment other than the first embodiment.

Fifth Embodiment

First, the configuration is described. The basic configuration of a pump 2 is to the same as that of the first embodiment (FIG. 2). However, the pump 2 has only the first control chamber 291, and does not have the second control chamber 292. To be more specific, the pump 2 does not include the second protrusion 242 and the second sealing member 262. The basic configuration of a control valve 7 is to the same as that in the fourth embodiment (FIG. 21). The basic configuration of a control passage 43 is that the same as in the first embodiment (FIG. 1). However, the control passage 43 includes only the first feedback passage 431 which is branched from the discharge passage 41, and does not include the second feedback passage 432. The first feedback passage 431 includes a supply passage 433, a communication passage 434, and a drainage passage 435. One end side of the supply passage 433 is branched from the discharge passage 41, and the other end of the supply passage 433 is connected to the supply port 803 B of the control valve 7. One end of the communication passage 434 is connected to the communication port 804 B of the control valve 7, and the other end of the communication passage 434 is connected to the first control chamber 291. One end of the drainage passage 435 is connected to the drainage port 805 of the control valve 7, and the other end of the drainage passage 435 is connected to an oil pan 400. The cam ring 24 receives a pressure p of working oil in the first control chamber 291 (control hydraulic pressure p). A first region 246 of the outer peripheral surface 245 of the cam ring functions as a pressure receiving surface which receives a control hydraulic pressure p. Other configurations are to the same as those in the first embodiment and hence, corresponding constitutional elements are given the same reference numerals, and the repeated description of such constitutional elements is omitted.

Next, the manner of operation is described. A cam ring 24 is biased by a spring force Fs of a spring 25 to one side in the rotational direction about a pin 27 (to the side where the amount of increase or decrease in volume of each of the plurality of working chambers 28 increases, and the amount of eccentricity Δ increases). The cam ring 24 is biased to the other side in the rotational direction about the pin 27 (to the side where the amount of increase or decrease in volume of each of the plurality of working chambers 28 decreases, and the amount of eccentricity Δ decreases) by a force Fp1 which is caused by a control hydraulic pressure P. When a force Fp1 becomes larger than a spring force Fs, the cam ring 24 oscillates to the other side in the above-mentioned rotational direction and hence, the amount of eccentricity Δ (capacity) reduces. When a force Fp1 becomes smaller than a spring force Fs, the cam ring 24 oscillates to one side in the rotational direction about the pin 27 (to the side where the amount of eccentricity Δ increases) and hence, capacity increases. When an electromagnetic force fm is smaller than a spring force fs, the spool 81 moves to one side in the axial direction toward the initial position so that an amount of working oil drained from the first control chamber 291 increases whereby a force Fp1 decreases. When a force Fp1 is smaller than a spring force Fs, an amount of eccentricity Δ increases. When an electromagnetic force fm is larger than a spring force fs, the spool 81 moves to the other side in the axial direction. Accordingly, working oil is introduced into the first control chamber 291 and, the amount of working oil drained from the first control chamber 291 decreases so that a force Fp1 increases. When a force Fp1 becomes larger than a spring force Fs, an amount of eccentricity Δ decreases.

As described above, the present invention is also applicable to the pump 2 having the configuration where the control mechanism 3 (control valve 7) controls a pressure in the first control chamber 291. The characteristic of main gallery hydraulic pressure P with respect to engine speed Ne can be easily caused to approximate the desired characteristic. Additionally, ease of control can be improved. The manner of other operations and advantageous effects are to the same as those in the first embodiment. The configuration of this embodiment is also applicable to an embodiment other than the first embodiment.

OTHER EMBODIMENTS

Embodiments for carrying out the present invention have been described heretofore with reference to drawings. However, the specific configuration of the present invention is not limited to any of the above-mentioned embodiments. The present invention also includes embodiments to which design change or the like is added without departing from the gist of the invention. Within a range where at least a portion of the above-mentioned problem can be solved or a range where at least a portion of the above-mentioned advantageous effects can be acquired, respective constitutional elements described in the claims the specification may be arbitrarily combined or omitted. For example, the pump may also be used in a working oil supply system for a mechanical device other than a working oil supply system for an automobile or an engine. The specific configuration of the vane pump is not limited to the embodiments, and may be suitably changed. It is sufficient that the pump is a variable capacity pump, and members other than vanes may be used as pump structures. A member other than a cam ring may be used as a movable member which causes the amount of increase or decrease in volume of each of the plurality of working chambers during the rotation of pump structures to be varied. For example, a pump may be formed of a trochoid gear pump. In this case, by disposing an outer rotor, which is an external gear, so as to allow eccentric movement, and by disposing a control chamber and a spring on the outer peripheral side of the outer rotor, it is possible to realize a variable capacity pump (the outer rotor corresponds to the movable member).

Each of the arithmetic operation portion and the reception portion of the ECU is realized by software in a microcomputer in the embodiments. However, the arithmetic operation portion or the reception portion of the ECU may be realized by an electronic circuit. An arithmetic operation means not only an arithmetic operation using a formula, but also general processing performed on software. The reception portion may be an interface of a microcomputer, or may be software in the microcomputer. A control signal may be a signal relating to a current value, or a signal relating to the thrust of a solenoid. A method for controlling an electric current to be supplied to a solenoid is not limited to PWM control. Current values which correspond to rotational speeds of an engine may be set in advance by a map. Characteristic information which causes a control signal of a solenoid to be varied according to variation in engine speed may be realized by performing an arithmetic operation instead of being realized by a map in a microcomputer.

[Other Aspects which May be Understood Based on Embodiments]

Other aspects which may be understood based on the above-mentioned embodiment are described hereinafter.

(1) In one aspect, a variable capacity pump includes:

a housing including a pump accommodating chamber therein;

a pump structure disposed in the pump accommodating chamber, and configured to vary volumes of a plurality of working chambers with rotation, the pump structure being configured to discharge from a discharge portion working oil introduced from an intake portion by being rotationally driven;

a movable member disposed in the pump accommodating chamber, and accommodating the pump structure to define the plurality of working chambers, the movable member being configured to cause an amount of increase or decrease in volume of each of the plurality of working chambers during rotation of the pump structure to be varied by moving so that an amount of eccentricity of a center of an inner periphery of the movable member from a center of rotation of the pump structure varies;

a first biasing member disposed in the pump accommodating chamber in a state where a set load is applied to the first biasing member, and configured to bias the movable member in a direction that the amount of increase or decrease in volume of each of the plurality of working chambers increases;

a first control chamber which is disposed between the pump accommodating chamber and the movable member, and into which the working oil discharged from the discharge portion is introduced, a volume of the first control chamber increasing with movement of the movable member in a direction opposing a biasing force of the first biasing member;

a second control chamber which is disposed between the pump accommodating chamber and the movable member, and into which the working oil discharged from the discharge portion is introduced through a passage, a volume of the second control chamber being variable with movement of the movable member; and

a control valve provided in the passage, and configured to vary, with movement of a valve element, a cross-sectional area of a flow passage, through which working oil in the second control chamber is drained to a low pressure portion, while making the discharge portion and the second control chamber communicate with each other.

(2) In a more preferred aspect, in the above-mentioned aspect,

with movement of the valve element in a first direction, the control valve increases the cross-sectional area of the flow passage, through which working oil in the second control chamber is drained to the low pressure portion, while decreasing a cross-sectional area of a flow passage, through which working oil is introduced from the discharge portion to the second control chamber.

(3) In another preferred aspect, in any one of the above-mentioned aspects,

with movement of the valve element in a second direction, the control valve decreases the cross-sectional area of the flow passage, through which working oil in the second control chamber is drained to the low pressure portion, while increasing a cross-sectional area of a flow passage through which working oil is introduced from the discharge portion to the second control chamber.

(4) In still another preferred aspect, in any one of the above-mentioned aspects,

the control valve is configured to continuously change a position of the valve element.

(5) In still another preferred aspect, in any one of the above-mentioned aspects,

the control valve is configured to stop the valve element at any position.

(6) In still another preferred aspect, in any one of the above-mentioned aspects,

the control valve includes a solenoid portion configured to generate an electromagnetic force for biasing the valve element.

(7) In still another preferred aspect, in any one of the above-mentioned aspects,

the solenoid portion is configured to move the valve element to any position according to a control signal.

(8) In still another preferred aspect, in any one of the above-mentioned aspects,

the valve element is integrally coupled to a plunger of the solenoid portion.

(9) In still another preferred aspect, in any one of the above-mentioned aspects,

the control valve includes a hollow member which accommodates the valve element, and which has a first port communicating with the discharge portion, a second port communicating with the second control chamber, and a third port communicating with a low pressure portion, openings of the first port, the second port, and the third port being formed on an inner periphery of the hollow member.

(10) In still another preferred aspect, in any one of the above-mentioned aspects,

the control valve includes a solenoid portion configured to generate an electromagnetic force for biasing the valve element, and

the valve element includes

a first land portion disposed on a first port side, and biased to one side by the solenoid portion,

a second land portion disposed on a third port side, and biased to an opposite side by a second biasing member, and

a connecting portion connecting the first land portion and the second land portion with each other.

(11) In still another preferred aspect, in any one of the above-mentioned aspects,

the second land portion varies an area of the opening of the third port as the first land portion varies an area of the opening of the first port.

(12) In still another preferred aspect, in any one of the above-mentioned aspects,

the control valve includes a solenoid portion configured to generate an electromagnetic force for biasing the valve element,

the opening of the second port is disposed between the opening of the first port and the opening of the third port,

the valve element includes a land portion biased to one side by the solenoid portion, and biased to the opposite side by a second biasing member, and

the land portion varies an area of the opening of the second port communicating with the opening of the first port, and an area of the opening of the second port communicating with the opening of the third port.

(13) In still another preferred aspect, in any one of the above-mentioned aspects,

a volume of the second control chamber increases with movement of the movable member in the same direction as a direction of a biasing force of the first biasing member.

(14) In still another preferred aspect, in any one of the above-mentioned aspects,

the movable member includes a first pressure receiving surface facing the first control chamber, and a second pressure receiving surface facing the second control chamber, and having a pressure receiving area larger than a pressure receiving area of the first pressure receiving surface.

(15) In still another preferred aspect, in any one of the above-mentioned aspects,

the movable member is configured to oscillate around a fulcrum in the pump accommodating chamber.

(16) In still another preferred aspect, in any one of the above-mentioned aspects,

the movable member is configured to perform a translational motion in the pump accommodating chamber.

(17) In still another preferred aspect, in any one of the above-mentioned aspects,

a volume of the second control chamber increases with movement of the movable member in a direction opposing the biasing force of the first biasing member.

(18) Further, from another view point, in one aspect, a variable capacity pump includes:

a housing including a pump accommodating chamber therein;

a pump structure disposed in the pump accommodating chamber, and configured to vary volumes of a plurality of working chambers with rotation, the pump structure being configured to discharge from a discharge portion working oil introduced from an intake portion by being rotationally driven;

a movable member disposed in the pump accommodating chamber, and accommodating the pump structure to define the plurality of working chambers, the movable member being configured to cause an amount of increase or decrease in volume of each of the plurality of working chambers during rotation of the pump structure to be varied by moving so that an amount of eccentricity of a center of an inner periphery of the movable member from a center of rotation of the pump structure varies;

a first control chamber which is disposed between the pump accommodating chamber and the movable member, and into which the working oil discharged from the discharge portion is introduced, a volume of the first control chamber increasing with movement of the movable member in one direction;

a second control chamber which is disposed between the pump accommodating chamber and the movable member, and into which the working oil discharged from the discharge portion is introduced through a passage, a volume of the second control chamber being variable with movement of the movable member;

a cylindrical member having a hollow shape, and including a first port communicating with the discharge portion, a second port communicating with the second control chamber, and a third port communicating with a low pressure portion, openings of the first port, the second port, and the third port being formed on an inner periphery of the cylindrical member; and

a control valve including a spool movable in the cylindrical member, and a solenoid portion configured to move the spool.

The spool includes a first large diameter portion configured to vary an area of the opening of the first port, and a second large diameter portion configured to vary an area of the opening of the third port, and the first large diameter portion and the second large diameter portion are disposed on the inner periphery of the cylindrical member within a range sandwiched between the first large diameter portion and the second large diameter portion such that the first port, the second port, and the third port are allowed to be at least partially open simultaneously.

(19) In one aspect, a working oil supply system for an internal combustion engine includes:

a variable capacity pump which introduces working oil discharged from a pump structure into a control chamber disposed around a movable member, which accommodates the pump structure therein, so as to move the movable member to vary an amount of eccentricity of a center of the movable member from a center of rotation of the pump structure, thus varying a pressure of working oil discharged from the pump structure to the internal combustion engine;

a pressure measuring portion configured to measure a pressure of working oil discharged from the pump structure;

a rotational speed measuring portion configured to measure a rotational speed of the internal combustion engine; and

a control portion which calculates a pressure difference between a pressure measured by the pressure measuring portion and a pressure of working oil which the internal combustion engine is required to have at the rotational speed measured by the rotational speed measuring portion, the control portion varying, when the rotational speed is equal to or more than a predetermined rotational speed and the pressure difference is larger than a predetermined pressure difference, a drainage amount of working oil from the control chamber to a low pressure portion while allowing working oil to be introduced into the control chamber until the pressure difference becomes equal to or less than the predetermined pressure difference.

(20) In a more preferred aspect, in the above-mentioned aspect,

the control portion does not drain working oil from the control chamber to the low pressure portion when the rotational speed is less than the predetermined rotational speed.

(21) In another preferred aspect, in any one of the above-mentioned aspects,

the control portion controls, when the rotational speed is equal to or more than the predetermined rotational speed and the pressure difference is equal to or less than the set pressure difference, a drainage amount of working oil from the control chamber to the low pressure portion at a predetermined fixed amount until the pressure difference becomes larger than the set pressure difference.

This application claims priority to Japanese patent application No. 2016-181736 filed on Sep. 16, 2016. The entire disclosure, including the specification, the claims, the drawings, and the abstract of Japanese patent application No. 2016-181736 filed on Sep. 16, 2016 is incorporated herein by reference.

REFERENCE SIGNS LIST

1 working oil supply system
2 variable capacity pump
20 housing body
200 pump accommodating chamber
201 intake opening (intake portion)
203 discharge opening (discharge portion)
22 rotor (pump structure)
23 vane (pump structure)
24 cam ring (movable member)
25 spring (first biasing member)
28 working chamber
291 first control chamber
292 second control chamber
3 control mechanism
4 passage
400 oil pan (low pressure portion)
6 engine control unit (control portion)
7 control valve
8 valve portion
81 spool (valve body)
9 solenoid portion

Claims

1. A variable capacity pump comprising:

a housing including a pump accommodating chamber therein;

a pump structure disposed in the pump accommodating chamber, and configured to vary volumes of a plurality of working chambers with rotation, the pump structure being further configured to discharge from a discharge portion working oil introduced from an intake portion by being rotationally driven;

a movable member disposed in the pump accommodating chamber, and accommodating the pump structure to define the plurality of working chambers, the movable member being configured to cause an amount of increase or decrease in volume of each of the plurality of working chambers during rotation of the pump structure to be varied by moving so that an amount of eccentricity of a center of an inner periphery of the movable member from a center of rotation of the pump structure varies;

a first biasing member disposed in the pump accommodating chamber in a state where a set load is applied to the first biasing member, and configured to bias the movable member in a direction that the amount of increase or decrease in volume of each of the plurality of working chambers increases;

a first control chamber which is disposed between the pump accommodating chamber and the movable member, and into which the working oil discharged from the discharge portion is introduced, a volume of the first control chamber increasing with movement of the movable member in a direction opposing a biasing force of the first biasing member;

a second control chamber which is disposed between the pump accommodating chamber and the movable member, and into which the working oil discharged from the discharge portion is introduced through a passage, a volume of the second control chamber being variable with movement of the movable member; and

a control valve provided in the passage, and configured to vary, with movement of a valve element, a cross-sectional area of a flow passage, through which working oil in the second control chamber is drained to a low pressure portion, while making the discharge portion and the second control chamber communicate with each other.

2. The variable capacity pump according to claim 1, wherein

with movement of the valve element in a first direction, the control valve increases the cross-sectional area of the flow passage, through which working oil in the second control chamber is drained to the low pressure portion, while decreasing a cross-sectional area of a flow passage, through which working oil is introduced from the discharge portion to the second control chamber.

3. The variable capacity pump according to claim 1, wherein

with movement of the valve element in a second direction, the control valve decreases the cross-sectional area of the flow passage, through which working oil in the second control chamber is drained to the low pressure portion, while increasing a cross-sectional area of a flow passage through which working oil is introduced from the discharge portion to the second control chamber.

4. The variable capacity pump according to claim 1, wherein

the control valve is configured to continuously change a position of the valve element.

5. The variable capacity pump according to claim 4, wherein

the control valve is configured to stop the valve element at any position.

6. The variable capacity pump according to claim 1, wherein

the control valve includes a solenoid portion configured to generate an electromagnetic force for biasing the valve element.

7. The variable capacity pump according to claim 6, wherein

the solenoid portion is configured to move the valve element to any position according to a control signal.

8. The variable capacity pump according to claim 6, wherein

the valve element is integrally coupled to a plunger of the solenoid portion.

9. The variable capacity pump according to claim 1, wherein

the control valve includes a hollow member which accommodates the valve element, and which has a first port communicating with the discharge portion, a second port communicating with the second control chamber, and a third port communicating with a low pressure portion, openings of the first port, the second port, and the third port being formed on an inner periphery of the hollow member.

10. The variable capacity pump according to claim 9, wherein

the control valve includes a solenoid portion configured to generate an electromagnetic force for biasing the valve element, and

the valve element includes

a first land portion disposed on a first port side, and biased to one side by the solenoid portion,

a second land portion disposed on a third port side, and biased to an opposite side by a second biasing member, and

a connecting portion connecting the first land portion and the second land portion with each other.

11. The variable capacity pump according to claim 10, wherein

the second land portion varies an area of the opening of the third port as the first land portion varies an area of the opening of the first port.

12. The variable capacity pump according to claim 9, wherein

the control valve includes a solenoid portion configured to generate an electromagnetic force for biasing the valve element,

the opening of the second port is disposed between the opening of the first port and the opening of the third port,

the valve element includes a land portion biased to one side by the solenoid portion, and biased to the opposite side by a second biasing member, and

the land portion varies an area of the opening of the second port communicating with the opening of the first port, and an area of the opening of the second port communicating with the opening of the third port.

13. The variable capacity pump according to claim 1, wherein

a volume of the second control chamber increases with movement of the movable member in the same direction as a direction of a biasing force of the first biasing member.

14. The variable capacity pump according to claim 13, wherein

the movable member includes a first pressure receiving surface facing the first control chamber, and a second pressure receiving surface facing the second control chamber, and having a pressure receiving area larger than a pressure receiving area of the first pressure receiving surface.

15. The variable capacity pump according to claim 13, wherein

the movable member is configured to oscillate around a fulcrum in the pump accommodating chamber.

16. The variable capacity pump according to claim 13, wherein

the movable member is configured to perform a translational motion in the pump accommodating chamber.

17. The variable capacity pump according to claim 1, wherein

a volume of the second control chamber increases with movement of the movable member in a direction opposing the biasing force of the first biasing member.

18. A variable capacity pump comprising:

a housing including a pump accommodating chamber therein;

a pump structure disposed in the pump accommodating chamber, and configured to vary volumes of a plurality of working chambers with rotation, the pump structure being configured to discharge from a discharge portion working oil, which is introduced from an intake portion by being rotationally driven;

a movable member disposed in the pump accommodating chamber, and accommodating the pump structure to define the plurality of working chambers, the movable member being configured to cause an amount of increase or decrease in volume of each of the plurality of working chambers during rotation of the pump structure to be varied by moving so that an amount of eccentricity of a center of an inner periphery of the movable member from a center of rotation of the pump structure varies;

a first control chamber which is disposed between the pump accommodating chamber and the movable member, and into which working oil discharged from the discharge portion is introduced, a volume of the first control chamber increasing with movement of the movable member to one side,

a second control chamber which is disposed between the pump accommodating chamber and the movable member, and into which the working oil discharged from the discharge portion is to be introduced through a passage, a volume of the second control chamber being variable with movement of the movable member;

a cylindrical member having a hollow shape, and including a first port communicating with the discharge portion, a second port communicating with the second control chamber, and a third port communicating with a low pressure portion, openings of the first port, the second port, and the third port being formed on an inner periphery of the cylindrical member; and

a control valve including a spool movable in the cylindrical member, and a solenoid portion configured to move the spool, wherein

the spool includes a first large diameter portion configured to vary an area of the opening of the first port, and a second large diameter portion configured to vary an area of the opening of the third port, and

the first large diameter portion and the second large diameter portion are disposed on the inner periphery of the cylindrical member within a range sandwiched between the first large diameter portion and the second large diameter portion such that the first port, the second port, and the third port are allowed to be at least partially open simultaneously.

19. A working oil supply system for an internal combustion engine, the working oil supply system comprising:

a variable capacity pump which introduces working oil discharged from a pump structure into a control chamber disposed around a movable member, which accommodates the pump structure therein, so as to move the movable member to vary an amount of eccentricity of a center of the movable member from a center of rotation of the pump structure, thus varying a pressure of working oil discharged from the pump structure to the internal combustion engine;

a pressure measuring portion configured to measure a pressure of working oil discharged from the pump structure;

a rotational speed measuring portion configured to measure a rotational speed of the internal combustion engine; and

a control portion which calculates a pressure difference between a pressure measured by the pressure measuring portion and a pressure of working oil which the internal combustion engine is required to have at the rotational speed measured by the rotational speed measuring portion, the control portion varying, when the rotational speed is equal to or more than a predetermined rotational speed, and the pressure difference is larger than a predetermined pressure difference, a drainage amount of working oil from the control chamber to a low pressure portion while allowing working oil to be introduced into the control chamber until the pressure difference becomes equal to or less than the predetermined pressure difference.

20. The working oil supply system for an internal combustion engine according to claim 19, wherein

the control portion does not drain working oil from the control chamber to the low pressure portion when the rotational speed is less than the predetermined rotational speed.